Methods and devices for applying energy to bodily tissues

ABSTRACT

Devices and methods are disclosed for treating tissue with microwave energy. Such devices and methods are able to treat cavities or surface tissue by creating one or more area or volumetric lesions. Also disclosed are flexible, low-profile devices that can be inserted non-invasively or minimally invasively near or into the target tissue as well as microwave antennas designed to generate ablation profiles that can ablate a large area or a large volume of target tissue in a single ablation. The devices include antennas wherein the field profile generated by an antenna is tailored and optimized for a particular clinical application. The antennas use unique properties of microwaves such as interaction of a microwave field with a metallic object and the use of additional shaping elements to shape the microwave field.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continutation of U.S. patent application Ser. No.12/603,349 filed Oct. 21, 2009 which is a non-provisional of U.S. PatentApplication Nos.: 61/113,189, filed on Nov. 10, 2008; 61/113,192, filedon Nov. 10, 2008; 61/113,194, filed on Nov. 10, 2008; 61/162,241, filedon Mar. 20, 2009; 61/162,244, filed on Mar. 20, 2009; and 61/222,409,filed on Jul. 1, 2009. The contents of which are incorporated herein byreference in their entireties.

FIELD OF THE INVENTION

This invention relates to devices and methods for ablation of softtissues of the body and, more specifically, to microwave ablationdevices designed to generate microwave fields for therapeutic tissueablation.

BACKGROUND OF THE INVENTION

There are several clinical conditions that can be treated by ablation.Examples of such conditions include cancer, Menorrhagia, atrialfibrillation, wrinkles, etc. Menorrhagia is one of the most commongynecological conditions in pre-menopausal women. It is characterized byexcessive menstrual blood loss. Objectively, Menorrhagia is defined asblood loss of more than 80 ml per menstrual cycle. The conditionseverely affects the quality of life of the affected women since it mayinterfere with physical activity, work and sexual activity. In somecases, it leads to iron deficiency anemia. Further, there is an emergingneed for an easy-to-use, low cost procedure among women who want toreduce or eliminate non-clinical menstrual bleeding for lifestylereasons.

The usual first line of treatment is drugs such as oral contraceptivepills and synthetic Progesterone supplements. However, drugs are noteffective in a significant percentage of patients.

In patients with refractory disease, the classical treatment ishysterectomy. Hysterectomy is an invasive surgery involving the surgicalremoval of the uterus—a major organ in the body. The surgery requires2-4 days of hospitalization and has a 3 to 6 week recovery period.Further, it carries surgical risks due to the use of general anesthesia.

As an alternative to hysterectomy, several techniques have beendeveloped that aim to destroy only the endometrium in a minimallyinvasive manner called endometrial ablation. Endometrial ablation can beperformed by a variety of techniques such as radiofrequency heating,circulating hot saline in the uterine cavity, microwave heating,cryodestruction, laser destruction, etc. Endometrial ablation in generalhas been established as an effective therapy for the treatment ofMenorrhagia. However, every current endometrial ablation technique hassome fundamental limitations. For example, the Hydrothermablator™ deviceby Boston Scientific circulates hot saline in the uterine cavity tothermally destroy the endometrium. Uterine size and shape is rarely alimitation to performing this procedure since the saline conforms wellto even an irregularly shaped endometrial surface. However, the deviceneeds a hysteroscope which adds to the procedure cost and complexity.Further the device is thick and rigid. Because of that, the procedurerequires significant anesthesia, usually in the form of conscioussedation or general anesthesia.

Currently, the market leader for endometrial ablation is Novasure™, adevice that uses radiofrequency energy delivered through a triangularthree dimensional metallic mesh to destroy the endometrial lining. Eventhough the device is the market leader, it has several fundamentaldisadvantages. The device shaft is thick and rigid. Thus a significantamount of cervical dilation is needed to introduce the device into theuterine cavity. Since cervical dilation is very painful, the procedurerequires significant anesthesia, usually in the form of conscioussedation or general anesthesia. Further, the fairly rigid, threedimensional, triangular metallic mesh is unable to conform toirregularly-shaped uterine cavities. This reduces the total potentialpool of patients that can be treated by the device. Also, the device isexpensive (˜$900). This limits the use of the devices not just indeveloping countries, but also in the U.S. In the U.S., the totalreimbursement for an endometrial ablation procedure performed in theoffice is fixed. When the cost of the expensive device is added to thecost of the personnel and equipment required for conscious sedation, theprofit margins of performing physicians shrink dramatically or evendisappear totally.

Thus, even though there are a variety of endometrial ablation products,there is still a need for a small-size, flexible, low-cost, easy to usedevice in this large and growing market.

BRIEF SUMMARY OF THE INVENTION

The present invention discloses devices and methods for treating tissuewith microwave energy. In several embodiments, microwave energy is usedfor ablating tissue. One application for such ablation is treatingmenorrhagia by endometrial ablation.

The present invention discloses methods and devices to create one ormore area or volumetric lesions. The present invention discloses variousembodiments of flexible, low-profile devices that can be insertednon-invasively or minimally invasively into or near the target tissue.

Some of the embodiments herein may be broadly described as microwavedevices comprising a transmission line (e.g. a coaxial cable) and anantenna at the distal end of the coaxial cable. The antenna comprises aradiating element that extends from the distal end of the coaxial cable.For example, the radiating element may be a continuation of the innerconductor of the coaxial cable or may be an additional element connectedto the inner conductor of the coaxial cable. The radiating elementradiates a microwave field that is characteristic of its specificdesign. The radiated microwave field causes agitation of polarizedmolecules, such as water molecules, that are within target tissue. Thisagitation of polarized molecules generates frictional heat, which inturn raises the temperature of the target tissue. Further, the microwavefield radiated by the radiating element may be shaped by one or moreshaping element(s) in the antenna. The shaping element(s) may beelectrically connected to the outer conductor of the coaxial cable.Several embodiments of the radiating element and the shaping element andcombinations thereof are described herein. A significant portion of thedisclosure discloses embodiments of ablation devices, wherein theradiating element is shaped like a loop and the shaping element isshaped like a loop. The cross section shapes of the radiating elementand shaping element may be designed to achieve the desired mechanicaland microwave properties. Examples of such cross section shapes include,but are not limited to round, oval, rectangular, triangular, elliptical,square, etc.

The present invention discloses several microwave antennas designed togenerate a unique ablation profile that can ablate an entire large areaor large volume target tissue in a single ablation. The ablation profilecan be purposely shaped by designing the antenna. For example, theablation profile may be designed to create a deeper ablation in thecenter of a target organ and shallower ablation towards the periphery ofthe target organ.

The antennas disclosed herein may be deployed before being placed in thevicinity of or inside of the target tissue. Alternately, the antennasmay be deployed after being placed in the vicinity of or inside of thetarget tissue. The deployment of the antennas disclosed herein may bedone by one of several methods. The antenna may simple be navigated tothe target tissue in a full deployed configuration. For example, theantenna may be navigated to the surface of liver in a full deployedconfiguration through a laparotomy. The antenna may be deployed throughan introducer in which the antenna is in a collapsed, low-profileconfiguration when inside the introducer and is deployed after theantenna exits the introducer. The antenna may be deployed after theantenna exits the introducer by one or more of: the elastic property ofthe antenna or its components, the super-elastic property of the antennaor its components, the shape memory property of the antenna or itscomponents, use of a mechanical deployment mechanism for the antenna orits components, use of one or more anatomical regions to change theshape of one or more antenna portions, etc. One or more portions of theantennas herein may be malleable or plastically deformable. This allowsthe user to shape an antenna to ensure better contact with target tissueor better navigation through the anatomy.

The devices disclosed herein comprise antennas wherein the ablationprofile generated by an antenna is tailored and optimized for aparticular clinical application. For example, in the embodiments whereina microwave antenna is used to ablate the wall of a cavity such as theuterine cavity, the ablation profile may be designed to ablatesubstantially the entire wall of the cavity without the need forrepositioning of the antenna.

The antennas disclosed herein may be conformable to acquire the shape ofa portion of the target anatomy or otherwise be shaped by one or moreportions of the target anatomy. For example, the antennas disclosedherein may be elastically flexible to conform to that shape of a smallcavity into which the antenna is deployed. The antennas disclosed hereinmay be sized and shaped to approximate the size and shape of the targetanatomy such as the uterine cavity.

The ablation devices disclosed herein may be designed to be slim andflexible. This allows the user to introduce such ablation devicesminimally invasively through small incisions or opening or evennon-invasively through natural openings or passageways. Examples ofminimally invasive introduction includes percutaneous introductionthrough the vasculature. Examples of non-invasive introduction includesintroduction from the anus, mouth or nostrils into the gastro-intestinaltract, introduction from the vagina into the female reproductive system,introduction from the urethra into the urinary system, introduction fromthe ear, nostrils or mouth into the ENT system, etc. The devices andmethods disclosed herein may be used to ablate diseased tissue orhealthy tissue or unwanted tissue in organs or artificially createdcavities. The devices disclosed herein may be introduced throughlaparoscopic, thoracoscopic, cystoscopic, hysteroscopic or otherendoscopic openings or instrumentation into or near organs or bodilycavities. The methods disclosed herein may be performed under real-timemonitoring e.g. by direct visual observation, hysteroscopy, cystoscopy,endoscopy, laparoscopy, ultrasound imaging, radiologic imaging, etc.

Various additional features may be added to the devices disclosed hereinto confer additional properties to the devices disclosed herein.Examples of such features include, but are not limited to one or morelumens, ability to apply a vacuum or suction to the target anatomy,ability to visualize one or more regions of the target anatomy, abilityto limit the depth of insertion into the target anatomy, ability todeploy the antenna, ability to connect to a source of energy, etc.

Several of the method and device embodiments are designed to minimizethe use of anesthesia such that the methods may potentially be performedusing only local anesthesia.

The dimensions or other working parameters of the devices disclosedherein may be adjustable or programmable based on user inputs. The userinput may be based on factors such as patient's anatomical dataincluding anatomical dimensions and the desired level of safety andefficacy.

In one variation, the present disclosure includes a medical device forapplying microwave energy to a surface within a tissue cavity. Forexample, the device can include a transmission line; a flexible antennaelectrically coupled to the transmission line and moveable between afirst undeployed configuration and a second deployed configuration, theantenna comprising an elongate first conductor arranged in a firstplanar profile when in the deployed configuration, wherein in thedeployed configuration the antenna is configured to generate avolumetric microwave field upon application of the microwave energy,where the first planar profile of the first conductor is selected basedupon the tissue cavity to produce the microwave field sized to thetissue cavity antenna such the microwave field applies energy tosubstantially an entire surface of the tissue cavity in a singleactivation without repositioning.

In an additional variations, the antenna as described herein can furthercomprise a second conductor electrically coupled to a shielding elementof the transmission line, where the second conductor comprises a secondplanar profile configured such that upon the application of microwaveenergy to the first conductor, the second conductor alters output of thefirst conductor to produce the volumetric microwave field.

The first planar profile can be shaped to generate the volumetricmicrowave field to apply energy to a uterine cavity. Moreover, adeployed configuration of the antenna can substantially approximate theshape of the uterine (or other) cavity. In any case, such cavityablating device will employ an antenna that can generate a volumetricmicrowave field to ablate the entire cavity in a selective manner. Inone example, when the antenna is used in a uterine endometrium, theantennae can be configured such that a lesion on the endometrium isdeeper in the center of the uterine cavity and is shallower at a cornualregion and shallower at a lower uterine region.

The present disclosure also includes methods of delivering energy to asurface of a cavity in tissue. These methods can include inserting amicrowave ablation device into the cavity, the microwave ablation devicecomprising a transmission line and a microwave antenna, where themicrowave antenna comprises a first planar conductor and a planarshaping element; applying energy to microwave ablation device, whereduring the application of energy, the planar shaping element alters theenergy output of the planar conductor to produce a volumetric microwavefield to deliver energy to substantially an entire surface of thecavity.

As described herein, one benefit of shaping the volumetric microwavefield to match the cavity allows for minimum treatment cycles or even asingle treatment cycle. Accordingly, the method can include applyingenergy to generate the volumetric microwave field in the cavity toprovide a therapeutically effective amount of energy to the cavitywithout repositioning the microwave antenna.

The method can also include the use of an introducer or sheath devicewhere the microwave antenna deploys through the sheath and into thecavity. The use of the sheath or introducer allows for cooling orsuction to be performed in the cavity. In alternative variations, thecooling or suction can take place through a shaft of the device therebyeliminating the need for a separate introducer or sheath.

The antennas disclosed herein may use unique properties of microwavessuch as the interaction of microwaves with additional shaping elements(e.g. metallic objects) in the antenna to shape the microwave field. Forexample, additional shaping elements in the antenna may be used tocreate a more distributed microwave field. The shaping elements in theantenna may also be used to improve the power deposition by the antenna.The additional elements in the antenna are not in direct electricalconduction with the inner conductor of the coaxial feed cable. Inseveral of the embodiments disclosed herein, a conductive shapingelement (e.g. a loop shaped element) connected to the outer conductor ofa coaxial feed line is used to shape the microwave field.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1A shows a view of an antenna of a microwave ablation deviceoptimized for endometrial ablation.

FIG. 1B shows a section of ablation device 100 of FIG. 1A through acoaxial cable.

FIG. 1C shows a view of an antenna similar to the antenna of FIG. 1Awithout a center loop.

FIGS. 1D and 1E show the front and side views respectively of the SARprofile generated by an antenna with a center loop similar to theantenna of FIG. 1A.

FIG. 1F shows the simulated return loss of an ablation device with anantenna of FIG. 1D.

FIG. 1G shows the front view of the SAR profile generated by the antennaof FIG. 1D without center loop.

FIG. 1H shows the simulated return loss of an ablation device with theantenna of FIG. 1G.

FIGS. 1I and 1J show the front and side views respectively of the SARprofile generated by an antenna with a center loop similar to theantenna of FIGS. 1D and 1E.

FIGS. 1K and 1L show two alternate embodiments of shapes of microwaveantennas of ablation devices.

FIG. 1M shows the substantially circular cross-section of the microwaveantenna of FIGS. 1K and 1L through plane 1M-1M.

FIG. 1N shows two alternate cross-sections of microwave antenna of FIGS.1K and 1L through plane 1N-1N.

FIGS. 2A -2C show the various steps of a method of using an ablationdevice for endometrial ablation.

FIG. 3 shows a first embodiment of an ablation system comprising anablation device slidably introduced within an introducing sheath.

FIG. 4 illustrates the key steps of an embodiment of a method ofendometrial ablation.

FIGS. 5A-5E illustrate the key steps of ablating uterine endometrium totreat menorrhagia using a collapsible microwave ablation antenna.

FIG. 6A shows a longitudinally un-constrained and laterally un-collapsedconfiguration of an embodiment of a microwave antenna.

FIG. 6B shows a longitudinally constrained and laterally un-collapsedworking configuration of the embodiment of a microwave antenna shown inFIG. 6A.

FIG. 6C shows the placement of the microwave antenna of FIGS. 6A and 6Bin a folded piece of tissue.

FIG. 6D shows the unfolded piece of tissue of FIG. 6C showing theplacement of the microwave antenna of FIGS. 6A and 6B in alongitudinally constrained and laterally un-collapsed workingconfiguration and the ablation obtained from the microwave antenna.

FIG. 6E shows an unfolded view of ablated tissue after the ablationshown in FIG. 6C.

FIG. 6F shows a view of the ablated tissue sliced through the plane6F-6F in FIG. 6E.

FIG. 6G shows a view of the ablated tissue sliced through the plane6G-6G in FIG. 6E.

FIGS. 7A and 7B illustrate two steps of a method of endometrial ablationwith a reduced uterine blood flow.

FIGS. 8A-8C show the steps of a method of using an ablation device 100with a deflectable or steerable antenna 104 being used for endometrialablation.

FIGS. 8D-8E show a method embodiment of treating a uterine cavity byablating a distal and a proximal region of the uterine cavity in twoseparate ablations.

FIG. 9 shows a method of simultaneously using two ablation devices 100to ablate the uterine endometrium.

FIGS. 10A and 10B show two methods of using a trans-cervical accessdevice in combination with a energy emitting device to treat a localregion of the uterus.

DETAILED DESCRIPTION OF THE INVENTION

This specification discloses multiple systems, structures and devices,and associated methods, which employ various aspects of the invention.While these systems, structures and devices, and associated methods, arediscussed primarily in terms of microwave based ablation systems usedfor ablating uterine endometrium, it should be appreciated that methodsand devices disclosed herein are applicable for use in other bodilystructures, as well. For example, the various aspects of the inventioncan be used for ablating tissue in, or adjacent to, the brain, prostateand other portions of the male urinary tract, gall bladder, uterus andother portions of the female reproductive tract, regions of thevasculature, intestine and other portions of the lower alimentary tract,stomach and other portions of the upper alimentary tract, liver andother digestive organs, lungs, skin, mucus membranes, kidneys,reproductive organs, or other organs or soft tissues of the body.

Several devices and methods disclosed herein are used to treatmenorrhagia by microwave thermal ablation. Microwave thermal ablationdoes not depend on the conduction of electricity to tissue unlike RFablation. Thus, devices using microwave thermal ablation such as thedevices disclosed herein don't need good contact with tissue. They canfunction well even without perfect contact with the target tissue. Thus,the devices disclosed herein do not require extremely precise placementin tissue, thereby reducing the dependence of procedure outcome onphysician skills. The devices herein are designed to have a distalmicrowave emitting antenna and a proximal shaft. The proximal shaftcomprises a flexible coaxial cable that delivers microwave energy from amicrowave generator to the microwave emitting portion. The shaft is slim(e.g. <3 mm) and flexible so that minimal forces are exerted on thecervix during the procedure. The flexible nature of the shaft enablesthe shaft to take the natural shape of passage during introductioninstead of distorting the natural shape of the passage by the shaft ofthe device. For example, when a device is introduced trans-cervicallyinto the uterus, the shaft may acquire the shape of introduction passagecomprising the vagina, cervical canal and uterine cavity instead ofdistorting one or more of the vagina, cervical canal and uterine cavity.The device shaft may be designed to be capable of bending by more than45 degrees when it experiences distorting forces by the anatomy.Further, the slim and flexible nature of the devices herein enables theprocedure to be performed without cervical dilation. Cervical dilationif needed is minimal. This dramatically reduces the discomfort to thepatient consequently significantly reducing the requirement ofanesthesia. This has tremendous clinical advantages since now theprocedure can be performed in the physician's office under localanesthesia.

All the experiments herein were performed at 0.915 GHz ISM band.Antennas, methods, etc. disclosed herein may be used with or withoutmodifications at other frequencies including, but not limited to ISMbands of 0.433 GHz, 2.45 GHz, 5.8 GHz, etc. The microwave powergenerator may be magnetron based or solid state. The microwave powergenerator may be single or multi-channel. The microwave power generatorused for the experiments comprised a Vector Network Analyzer (Agilent8753 series) and amplifier modules build in-house using transistors fromFreescale Semiconductor (Austin, Tex.). The power measurement was madeusing a power meter (ML2438A Power Meter, Anritsu Company, Richardson,Tex.). Similar devices and components can be used to design themicrowave generator for clinical use with the devices and methodsdisclosed herein.

In the experiments, where desired, a fiber optic thermometry system (FOTLab Kit by LumaSense Technologies, Santa Clara, Calif.) was used tomeasure the temperature at several locations in the tissue. The fiberoptic thermometry system was used since it has no metallic componentsthat can interfere with the microwave field. Similar non-interferingthermometry may be used to measure the temperature at one or morelocations during an ablation procedure.

Several embodiments of planar antennas 104 are also included invariations of the devices described herein. Such planar antennas 104 maybe used to ablate or otherwise treat planar or non-planar tissueregions. Such planar antennas 104 may comprise single or multiplesplines, curves or loops in a generally planar arrangement. Planarantennas 104 may be used for ablating a surface such as the surface oforgans such as liver, stomach, esophagus, etc. In a one embodiment, asingle microwave signal is fed to an antenna 104 through a transmissionline. Antenna 104 generates a microwave field. The near field portion ofthe microwave field generated by antenna 104 may be used for tissueablation. For example, Fig. 1A shows a view of a planar antenna of amicrowave ablation device designed for endometrial ablation. In FIG. 1A,microwave ablation device 100 comprises a transmission line (such as acoaxial cable 102) terminating in an antenna 104 at the distal end ofthe transmission line. In one embodiment, a single microwave signal isfed to antenna 104 through coaxial cable 102. The shape of antenna 104is substantially triangular and has a wider distal region and a narrowerproximal region. This shape is similar to the shape of the uterinecavity and thus conforms to the shape of the uterine cavity. Antenna 104generates a microwave field. The near field of the microwave fieldgenerated by antenna 104 is used for endometrial ablation. In FIG. 1A,antenna 104 comprises a radiating element in the form of an outer loop112 and a shaping element in the form of a bent or curved metalliccenter loop 114. Outer loop 112 and center loop 114 may physically toucheach other when deployed in the anatomy. In one embodiment, outer loop112 is a continuation of the inner conductor of coaxial cable 102.Center loop 114 shapes or redistributes the microwave field radiated byouter loop 112. It should be noted that there is no direct electricalconduction between outer loop 112 and center loop 114. When microwaveenergy is delivered through coaxial cable 102 to antenna 104, a firstmicrowave field is emitted by outer loop 112. The first microwave fieldinteracts with center loop 114. This interaction induces a leakagecurrent on center loop 114. The leakage current in turn creates a secondmicrowave field. The first microwave field and the second microwavefield together combine to produce a unique shaped microwave field ofantenna 104 that is clinically more useful that the unshaped microwavefield generated by an antenna 104 comprising only outer loop 112. Thusthe original microwave field is redistributed by the design of centerloop 114. Center loop 114 alone is not capable of functioning as anantenna; rather center loop 114 shapes or redistributes theelectromagnetic or microwave field emitted by outer loop 112 to producea shaped microwave field that is clinically more useful. Further, thecombination of outer loop 112 and center loop 114 improves the powerdeposition of antenna 104.

It should be noted that there is no direct electrical conduction betweenouter loop 112 and center loop 114. Antenna 104 further comprises one ormore antenna dielectrics 116 covering one or more portions of one orboth of: outer loop 112 and s center loop 114. In FIG. 1A, an antennadielectric 116 covers the proximal portion of outer loop 112. Any of theantenna dielectrics 116 disclosed herein may be used to shape themicrowave field and to optimize the performance of antenna 104. Any ofthe antenna dielectrics 116 disclosed herein may be one or moreconducting polymers.

A microwave field couples to the nearest conductive path. In severalembodiments of antenna 104 disclosed herein, the nearest conductive pathis provided by center loop 114. Thus the microwave field couples tocenter loop 114 instead of coupling to the shielding element of thetransmission line (e.g. the outer conductor 106 of the feeding coaxialcable 102). Therefore, minimal microwave field is coupled proximally tothe shielding element of the transmission line. This in turn creates aunique, shaped or redistributed microwave field that does notsignificantly extend proximally to antenna 104 as shown in FIGS. 1D and1I.

In one embodiment, outer loop 112 has no sharp corners. Sharp corners inouter loop 112 may cause the field to concentrate in the vicinity of thesharp corners. In one embodiment, the minimal radius of curvature of acorner in outer loop 112 is at least 0.5 mm. In the embodiment in FIG.1A, the radius of curvature of corner regions 154 and 156 in outer loop112 is about 1 mm+/−0.3 mm.

In one embodiment, antenna 104 has a shape that substantiallyapproximates the shape of the body organ to be ablated. For example,antennas in FIGS. 1A, 1D and 1I have a roughly triangular, planar shapethat approximates the roughly triangular, planar shape of the uterinecavity and is especially suited for endometrial ablation. The antennas104 may be positioned such that the plane of the antenna is parallel tothe plane of the uterine cavity. The proximal portion of the antenna 104is directed towards the cervix and corner regions 154 and 156 of outerloop 112 are directed towards the fallopian tubes. However, as mentionedbefore, microwave thermal ablation does not necessarily require perfectcontact with all of the target tissue. Thus antenna 104 is able toablate all or substantially all of the endometrium. The entireendometrium can be ablated in a single ablation by antenna 104 having asingle microwave antenna. Thus, repositioning of antenna 104 after anablation is not needed. This greatly reduces the amount of physicianskill needed for the procedure. Further, multiple antennas 104 are notneeded in ablation device 100. A single antenna 104 positioned at asingle location is able to ablate a therapeutically sufficient amount ofthe endometrium. This simplifies the design of ablation device 100.

Further, antenna 104 in the working, deployed configuration is generallyflat and sufficiently flexible such that during and after introductionand deployment of antenna 104 in the anatomy, the anatomy experiencesonly slight forces from antenna 104. This may be achieved by designingan antenna 104 comprising one or more flexible outer loop 112, one ormore flexible center loop 114 and one or more flexible antennadielectrics 116. The plane of outer loop 112 is substantially parallelto the plane of center loop 114. Thus, the uterine walls experience onlyslight forces from antenna 104. This in turn reduces or eliminates thedistension of the uterine wall thereby reducing the discomfort to thepatient. This in turn further reduces the anesthesia requirements.Flexible antenna 104 may easily be introduced in a collapsed, undeployedconfiguration through a small lumen thereby eliminating or minimizingany cervical dilation. In such a collapsed, undeployed configuration,both outer loop 112 and center loop 114 are in a small profile,linearized configuration. The lack of cervical dilation dramaticallyreduces the discomfort to the patient consequently significantlyreducing the requirement of anesthesia. This has tremendous clinicaladvantages since now the procedure can be performed in the physician'soffice under local anesthesia. In the collapsed configuration, outerloop 112 and center loop 114 may be closer to each other than in thenon-collapsed configuration. This enables the introduction of antenna104 through narrow catheters, shafts, introducers and other introducingdevices. Further, this enables the introduction of antenna 104 throughsmall natural or artificially created openings in the body.

Further, flat and flexible antenna 104 in FIG. 1A in its deployedconfiguration has an atraumatic distal end in which the distal region ofantenna 104 is wider than the proximal portion of antenna 104. Thisdesign creates an atraumatic antenna 104 which in turn reduces the riskof perforation of the uterus. The flexible nature of antenna enablesantenna 104 to take the natural shape of passage during introductioninstead of distorting the passage. For example, when antenna 104 isintroduced trans-cervically into the uterus, antenna 104 may acquire theshape of introduction passage comprising the vagina, cervical canal anduterine cavity instead of distorting one or more of the vagina, cervicalcanal and uterine cavity.

In one embodiment, the length of outer loop 112 measured along the outerloop 112 from the distal end of coaxial cable 102 or other transmissionline until the distal end of outer loop 112 is an odd multiple of onequarter of the effective wavelength at one of: 433 MHz ISM band, 915 MHzISM band, 2.45 GHz ISM band and 5.8 GHz ISM band. In one embodiment of adeployed configuration of antenna 104 as shown in FIG. 1A, the length ofouter loop 112 measured along the outer loop 112 from the distal end ofcoaxial cable 102 until the distal end 158 of outer loop 112 is aboutthree quarters of the effective wavelength at the 915 MHz ISM band. Theeffective wavelength is dependent on the medium surrounding the antennaand the design of an antenna dielectric on the outer loop 112. Thedesign of the antenna dielectric includes features such as the type ofdielectric(s) and thickness of the dielectric layer(s). The exact lengthof the outer loop 112 is determined after tuning the length of outerloop 112 to get good impedance matching. The length of the outer loop112 in one embodiment is 100+/−15 mm. In one embodiment, the width ofdeployed outer loop 112 is 40+/−15 mm and the longitudinal length ofdeployed outer loop 112 measured along the axis of coaxial cable 102 is35+/−10 mm. In the embodiment shown in FIG. 1A, distal end 158 of outerloop 112 is mechanically connected to the distal end of coaxial cable102 by an elongate dielectric piece 160.

In one embodiment, the proximal portion of outer loop 112 is designed tobe stiffer and have greater mechanical strength than the distal portion.In the embodiment shown in FIG. 1A, this may be achieved by leavingoriginal dielectric material 110 of coaxial cable 102 on the proximalportion of outer loop 112. In an alternate embodiment, this is achievedby coating the proximal portion of outer loop 112 by a layer of antennadielectric.

In the embodiment shown in FIG. 1A, the cross sectional shape of outerloop 112 may or may not be uniform along the entire length of outer loop112. In this embodiment, the proximal portion of outer loop 112 is acontinuation of the inner conductor of coaxial cable 102. This portionhas a substantially circular cross section. A middle portion of outerloop 112 has a substantially flattened or oval or rectangular crosssection. The middle portion may be oriented generally perpendicular tothe distal region of coaxial cable 102 in the deployed configuration.The middle portion of outer loop 112 is mechanically designed to bend ina plane and comprise one or more bends after deployment in the anatomy.This in turn ensures that the distal most region of ablation device 100is atraumatic and flexible enough to conform to the target tissueanatomy. This helps in the proper deployment of outer loop 112 in theuterus. In one embodiment, the middle portion of outer loop 112 is acontinuation of inner conductor of coaxial cable 102 and is flattened.In one embodiment, the distal most portion of outer loop 112 is acontinuation of inner conductor of coaxial cable 102 and isnon-flattened such that it has a circular cross section.

One or more outer surfaces of outer loop 112 may be covered with one ormore layers of antenna dielectrics 116. One or more outer surfaces ofcenter loop 114 may be covered with one or more layers of antennadielectrics 116. The thickness and type of antenna dielectric materialalong the length of outer loop 112 is engineered to optimize themicrowave field shape. In one embodiment shown in FIG. 1A, every portionof outer loop 112 is covered with some antenna dielectric material suchthat no metallic surface of outer loop 112 is exposed to tissue. Thus,in the embodiment of FIG. 1A, outer loop 112 is able to transmit amicrowave field into tissue, but unable to conduct electricity totissue. Thus, outer loop 112 is electrically insulated from surroundingtissue. Thus, in the embodiment of FIG. 1A, there is no electricalconduction and no conductive path between outer loop 112 and center loop114 even though outer loop 112 and center loop 114 may physically toucheach other when deployed in the anatomy. Examples of dielectricmaterials that can be used as antenna dielectrics in one or moreembodiments disclosed herein include, but are not limited to EPTFE,PTFE, FEP and other floropolymers, Silicone, Air, PEEK, polyimides,cyanoacrylates, epoxy, natural or artificial rubbers and combinationsthereof. In the embodiment of FIG. 1A, the antenna dielectric 116 on theproximal portion of outer loop 112 is a continuation of the dielectric110 of coaxial cable 102. There may be an additional layer of a stifferantenna dielectric 116 over this later of antenna dielectric 116. In theembodiment of FIG. 1A, the dielectric on the middle portion of outerloop 112 is a silicone layer with or without impregnated air or asilicone tube enclosing a layer of air. In the embodiment of FIG. 1A,the dielectric on the distal most portion of outer loop 112 is asilicone layer with or without impregnated air or a silicone tubeenclosing a layer of air or EPTFE. The thickness of an antennadielectric on any portion of outer loop 112 may vary along the length ofouter loop 112. Further, the cross section of an antenna dielectric onany portion of outer loop 112 may not be symmetric. The variousconfigurations of the antenna dielectric are designed to achieve thedesired ablation profile as well as achieve the desired impedancematching or power efficiency. In an alternate embodiment, entire outerloop 112 is covered with silicone dielectric. In one such embodiment,the layer of silicone used to coat the distal most portion of outer loop112 may be thinner than the layer of silicone used to coat the middleportion of outer loop 112. The thinner silicone dielectric compensatesfor the lower field strength that normally exists at the distal mostportion of a radiating element such as outer loop in FIG. 1A. Thus, themicrowave field is made more uniform along the length of outer loop 112.In one device embodiment, outer loop 112 is made of a metallic materialand the circumference of the metallic material of the distal region ofouter loop 112 is more than the circumference of the metallic materialof the middle portion of outer loop 112. This causes the siliconedielectric to stretch more at the distal portion than at the middleportion of outer loop 112. This in turn generates a thinner layer ofantenna dielectric at the distal portion of outer loop 112 than at themiddle portion of outer loop 112. In another embodiment, entire outerloop 112 is made from a single length of metallic wire of a uniformcrossection. In this embodiment, a tubular piece of silicone dielectricof varying thickness is used to cover outer loop 112. The tubularsilicone dielectric is used to cover the distal and middle portions ofouter loop 112 such that the layer of silicone dielectric is thinnernear the distal portion and thicker near the middle portion of outerloop 112.

In FIG. 1A, the shape of outer loop 112 is different from the shape ofcenter loop 114. Further, in FIG. 1A, outer loop 112 and center loop 114are both substantially planar and the plane of outer loop 112 issubstantially parallel to the plane of center loop 114. Further, in FIG.1A, both outer loop 112 and center loop 114 are bent or non-linear.

FIG. 1B shows a section of ablation device 100 of FIG. 1A through thedistal end of a coaxial cable 102. Coaxial cable 102 used herein isflexible and comprises an inner conductor 108 made of Nitinol with a Nicontent of 56%+/−5%. The outer diameter of inner conductor 108 is0.0172″+/−0.004″. Inner conductor 108 has a cladding or plating 120 of ahighly conductive metal such as Ag or Au. In one embodiment, innerconductor 108 comprises a silver cladding 120 of thickness0.000250″+/−0.000050″. Cladding 120 in turn is surrounded by dielectricmaterial 110. In one embodiment, dielectric material 110 is made ofexpanded PTFE with an outer diameter of 0.046″+/−0.005″. The dielectricmaterial 110 in turn is surrounded by the outer conductor 106. Outerconductor 106 acts as a shielding element to the microwave signalstransmitted by inner conductor 108. Further, outer conductor 106 shieldsthe microwave signals transmitted by inner conductor 108 from externalnoise. In one embodiment, outer conductor 106 comprises multiple strandsof Ag plated Cu. The multiple strands of outer conductor 106 arearranged such that the outer diameter of outer conductor 106 is0.057″+/−0.005″. Outer conductor 106 in turn is covered by an outerjacket 118. In one embodiment, outer jacket 118 is made of PTFE with anouter diameter of 0.065″+/−0.005″. Thus, the outer diameter of coaxialcable 102 is less than about 2 mm. Similar embodiment of coaxial cable102 may be designed that are flexible and have a diameter of less than 4mm. Further, coaxial cable 102 is sufficiently flexible such that itconforms to a curved introduction passage comprising the vagina and thecervical canal during insertion of antenna 104 into the uterine cavity.The low profile and flexibility of the coaxial cable 102 has tremendousclinical advantages since it requires minimal or no cervical dilationduring trans-cervical insertion. Coaxial cable 102 may be stiffened orstrengthened if desired by adding one or more stiffening orstrengthening elements such as jackets, braids or layers over coaxialcable 102. In FIG. 1B, the identity of coaxial cable 102 ends at thedistal end of outer conductor 106. The outer jacket 118 ends a smalldistance proximal to the distal end of outer conductor 106. Innerconductor 108, cladding 120 and dielectric material 110 extend distallyfrom the distal end of outer conductor 106 into antenna 104. Thus, theradiating element or outer loop 112 is electrically connected to innerconductor 108. Two proximal ends of center loop 114 are electricallyconnected to two regions on the outer conductor 106. In one embodiment,the two proximal ends of center loop 114 are electrically connected todiametrically opposite regions on the distal end of outer conductor 106.In one embodiment, the two proximal ends of center loop 114 are solderedto the distal end of outer conductor 106. In another embodiment, the twoproximal ends of center loop 114 are laser welded to the distal end ofouter conductor 106. The two proximal ends of center loop 114 may beconnected to the distal end of outer conductor 106 in variousconfigurations including, but not limited to lap joint and butt joint.In an alternate embodiment, at least one of the two proximal ends ofcenter loop 114 is not connected to the distal end of outer conductor106. For example, at least one of the two proximal ends of center loop114 may be electrically connected to a region of outer conductor 106that is proximal to the distal end of outer conductor 106.

In a method embodiment, when ablation device 100 is used for endometrialablation, antenna 104 of FIG. 1A generates a substantially uniformmicrowave field that is more concentrated in the center of the uterusand is less concentrated towards the cornual regions and towards thecervix or the lower uterine region. Thus, the depth of ablationgenerated by antenna 104 is deeper in the center of the uterus and isless deep towards the cornual regions and towards the cervix. Such aprofile is clinically desired for improved safety and efficacy. In oneembodiment, the ablation profile is shaped to ablate a majority of thebasalis layer of the uterine endometrium. The shape of the microwavefield in any of the embodiments herein may be substantially similar tothe shape of the uterine endometrium. In one embodiment, center loop 114is made of a round or flat wire. Examples of flat wires that can be usedto make center loop 114 are flat wires made of Ag or Au plated Nitinolor stainless steel with a cross sectional profile of about 0.025″×about0.007″. Such a loop shaped shaping element does not act as a shield forthe microwave field. This non-shielding action is visible in the SARpattern in FIG. 1D. In FIG. 1D, there is no sharp drop in the microwavefield intensity past center loop 114. In the embodiment of FIG. 1A,center loop 114 is roughly oval in shape. Two proximal ends of centerloop 114 are electrically attached to two circumferentially oppositeregions of the outer conductor of coaxial cable 102. In the embodimentof FIG. 1A, the width of center loop 114 is 13+/−5 mm and the length ofcenter loop 114 is 33+/−8 mm. When ablation device 100 is used forendometrial ablation, outer loop 112 and center loop 114 both contactthe endometrial tissue surface.

Center loop 114 may be mechanically independent from outer loop 112 ormay be mechanically attached to outer loop 112. In the embodiment shownin FIG. 1A, center loop 114 is mechanically independent from outer loop112 and lies on one side of outer loop 112. In an alternate embodiment,a portion of center loop 114 passes through the interior of outer loop112. In an alternate embodiment, a portion of center loop 114 ismechanically connected to outer loop 112. This may be done for example,by using an adhesive to connect a portion of center loop 114 to outerloop 112. In an alternate embodiment, one or more portions of centerloop 114 are mechanically connected to one or more portions of outerloop 112 by one or more flexible attachments.

Parts of center loop 114 may or may not be covered by one or more layersof antenna dielectric materials 116. In the embodiment of FIG. 1A, oneor more or all metallic surfaces of center loop 114 are exposed to thedevice environment.

Portions of outer loop 112 and center loop 114 may be made from one ormore of lengths of metals such as copper, Nitinol, aluminum, silver orany other conductive metals or alloys. One or more portions of outerloop 112 and center loop 114 may also be made from a metallized fabricor plastics.

FIGS. 1D and 1E show the front and side views respectively of the SARprofile generated by an antenna with a center loop similar to theantenna of FIG. 1A. In the embodiment in FIG. 1D, the distal end ofouter loop 112 is mechanically and non-conductively attached to a regionof outer loop 112 proximal to the distal end of outer loop 112. Thus,outer loop 112 has a substantially linear proximal region and a loopeddistal region. In one embodiment, the looped distal region may besubstantially triangular in shape as shown in FIG. 1D. Outer diameter ofantenna dielectric 116 on the proximal region of outer loop 112 may belarger than or substantially the same as the outer diameter of antennadielectric 116 on the looped distal region of outer loop 112. Antennadielectric 116 on the looped distal region of outer loop 112 may be alayer of silicone of varying thickness. Outer loop 112 may be made of asilver or gold clad metal such as Nitinol. Center loop 114 may be madeof a silver or gold clad metal such as Nitinol. In the embodiment shownin FIGS. 1D and 1E, center loop 114 is not covered with any antennadielectric 116. Thus the metallic surface of center loop 114 may beexposed to the surrounding. Outer loop 112 and center loop 114 mayphysically touch each other when deployed in the anatomy as shown inFIG. 1E. In FIG. 1D, the microwave field is shaped such that theablation at the center of antenna 104 will be deeper than the ablationat the corners of antenna 104. This is clinically desirable forendometrial ablation. Also, FIGS. 1D and 1E show that the microwavefield volumetrically envelops entire antenna 104. Also, FIGS. 1D and 1Eshow that the microwave field is substantially bilaterally symmetric.FIG. 1G shows the front view of the SAR profile generated by antenna 104of FIG. 1D without center loop 114. The microwave effect of shapingelement 114 in FIG. 1D can be seen by comparing FIG. 1D to FIG. 1G. FIG.1G shows a first unshaped field that is not shaped by shaping element114. When the antenna 104 comprises a shaping element 114 as shown inFIG. 1D, the antenna generates a shaped microwave field as shown in FIG.1D. It should be noted that in FIGS. 1D and 1E, the shaped microwavefield is more uniformly distributed over a wider area of the endometriumthan in FIG. 1G. In FIG. 1G, the unshaped microwave field is moreconcentrated at the distal end of coaxial cable 102. A more uniformlydistributed, shaped microwave field such as in FIGS. 1D and 1E isclinically desirable for endometrial ablation. Further when antenna 104of FIG. 1D is used for endometrial ablation, the microwave field isdistributed over a wider area of the endometrium that the microwavefield generated by antenna 104 of FIG. 1G. This can be seen by comparingthe SAR profile distal to the distal end of coaxial cable 102 in FIGS.1D and 1E to the SAR profile distal to the distal end of coaxial cable102 in FIG. 1G. Further, in FIG. 1G, a portion of the unshaped microwavefield extends to a significant distance proximal to the distal end ofcoaxial cable 102. In FIGS. 1D and 1E, an insignificant portion of themicrowave field extends proximally to the distal end of coaxial cable102. Thus the microwave field profile of FIGS. 1D and 1E is advantageousover the microwave field profile of FIG. 1G since it limits collateraldamage to healthy tissue. Thus the presence of center loop 114 shapesthe microwave field such that the microwave field is more distributed.In absence of center loop 114, the microwave field interacts with anelement of transmission line 102 such as the outer conductor of acoaxial cable. This results in a non-desirable profile of the microwavefield e.g. a concentrated field around the distal end of thetransmission line 102 as shown in FIG. 1G. This interaction can alsocause backward heating of coaxial cable 102 that may lead to collateraldamage of healthy tissue. Further, the combination of outer loop 112 andcenter loop 114 creates a more robust antenna 104 wherein theperformance of antenna 104 is less affected by distortions duringclinical use. Also, FIGS. 1D and 1E show that the microwave fieldvolumetrically envelops entire antenna 104.

Further, the SAR profile of FIG. 1D demonstrates that the entire uterineendometrium can be ablated in a single ablation. Thus the physician canposition antenna 104 at a first position and ablate substantially theentire uterine endometrium or a therapeutically sufficient amount ofendometrium to treat menorrhagia. Thus the physician does not need toreposition antenna 104 after a first endometrial ablation. In oneembodiment, a majority of endometrium is ablated. This novel aspect ofthe device and procedure greatly reduces the amount of time needed forthe procedure and also reduces the procedure risks and physician skillrequirements. In the embodiments disclosed herein, a combination ofdirect microwave dielectric heating and thermal conduction throughtissue is used to achieve the desired therapeutic effect. The thermalconduction evens out any minor variations in the microwave field andenables the creation of a smooth, uniform ablation. Further, the SARprofile of FIGS. 1D and 1E demonstrates that antenna 104 is capable ofablating an entire volume surrounding antenna 104 not just ablatingbetween the surfaces of outer loop 112 and center loop 114. Further, theSAR profile of FIGS. 1D and 1E demonstrates that antenna 104 is capableof ablating a tissue region without leaving any “gaps” of unablatedtissue within that tissue region. Further, the SAR profile of FIGS. 1Dand 1E demonstrates that the entire microwave field generated by antenna104 is used for ablation. The entire microwave field comprises themicrowave field around outer loop 112, the microwave field around centerloop 114, the microwave field between outer loop 112 and center loop 114and the field within center loop 114. Further, the SAR profile of FIGS.1D and 1E demonstrates that the microwave field is located all aroundouter loop 112 and is not shielded or reflected by center loop 114. Thuscenter loop 114 does not act as a shield or reflector in the embodimentshown in FIGS. 1D and 1E.

Various embodiments of antenna 104 may be designed to generate a varietyof shapes of SAR and/or the ablation profile. For example, antennas 104may be designed to generate substantially square, triangular,pentagonal, rectangular, round or part round (e.g. half round, quarterround, etc.), spindle-shaped or oval SARs or ablation patterns.

FIG. 1F shows the simulated return loss of an ablation device withantenna 104 of FIG. 1D. The simulated return loss shows good matching(about −11 dB) at 915 MHz. FIG. 1H shows the simulated return loss of anablation device with an antenna of FIG. 1G. The simulation shows areturn loss of about −7.5 dB at 915 MHz. Thus, the presence of centerloop 114 also improves the matching and increases the power efficiency.In the presence of center loop 114, microwave power is delivered moreefficiently to the tissue and not wasted as heat generated withinablation device 100.

Shaping element 114 also increases the frequency range (bandwidth) overwhich antenna 104 delivers an acceptable performance. If the graphs inFIG. 1F and 1H are compared, at a cutoff of −10 dB, the acceptablefrequency range in the embodiment containing shaping element 114 is morethan 0.52 GHz (spanning from approximately 0.88 GHz to more than 1.40GHz). The acceptable frequency range in the comparable embodiment ofFIG. 1G without shaping element 114 is only about 0.18 GHz (spanningfrom approximately 0.97 GHz to approximately 1.15 GHz). Thus in thefirst case, a larger frequency range (bandwidth) is available over whichantenna 104 delivers an acceptable performance. This in turn allows fora design of antenna 104 wherein minor distortions of antenna 104 duringtypical clinical use or due to minor manufacturing variations do notsignificantly affect the performance of antenna 104.

FIGS. 1I and 1J show the front and side views respectively of the SARprofile generated by an antenna with a center loop similar to theantenna of FIG. 1D. The general construction of the embodiment in FIG.1I is similar to the general construction of the embodiment in FIG. 1D.However, in FIG. 1I, the radius of curvature of the two distal edges ofthe looped distal region of outer loop 112 is more than thecorresponding radius of curvature in FIG. 1D. Further, the length of thesubstantially linear proximal region of outer loop 112 is less than thecorresponding length in FIG. 1D. Also, the design of antenna dielectric116 on antenna 104 in FIG. 11 is different from the design of antennadielectric 116 on antenna 104 in FIG. 1D. In one embodiment, antennadielectric 116 on the proximal region of outer loop 112 is made of alayer of PEEK over a layer of EPTFE. The PEEK layer increases themechanical strength of the proximal region of outer loop 112. In thisembodiment, the antenna dielectric 116 on the looped distal region ofouter loop 112 is silicone of varying thickness. The thickness of thesilicone antenna dielectric 116 on the more proximal portion of thelooped distal region of outer loop 112 may be more than the thickness ofsilicone antenna dielectric 116 on the more distal portion of the loopeddistal region of outer loop 112. Outer loop 112 may be made of a silveror gold clad metal such as Nitinol. Center loop 114 may be made of asilver or gold clad metal such as Nitinol. In the embodiment shown inFIGS. 1D and 1E, center loop 114 is not covered with any antennadielectric 116. Thus the metallic surface of center loop 114 may beexposed to the surrounding. Outer loop 112 and center loop 114 mayphysically touch each other when deployed in the anatomy as shown inFIG. 1E. The clinical advantages of the shape of the SAR profile ofantenna 104 in FIGS. 1I and 1J are similar to the clinical advantages ofthe SAR profile of antenna 104 in FIGS. 1D and 1E.

FIGS. 1K and 1L show two alternate embodiments of shapes of microwaveantenna 104 of ablation device 100. In FIGS. 1K and 1L, center loop 114is not shown. In FIG. 1K, microwave antenna 104 is roughly diamondshaped. The distal most region of microwave antenna 104 measured alongthe axis of coaxial cable 102 comprises a smooth corner. The microwaveantenna 104 in this embodiment is pre-shaped to form the shape as shownin FIG. 1K. Such a microwave antenna 104 can be collapsed to enableinsertion of microwave antenna 104 in a collapsed, low-profile,substantially linear, undeployed configuration though a lumen of adevice. In FIG. 1K, microwave antenna 104 is sized and shaped such thatwhen antenna 104 is deployed in the uterine cavity and pushed distallyby a user, the distal most region of microwave antenna 104 measuredalong the axis of coaxial cable 102 is pushed by the uterine fundus andflattened to achieve the configuration as shown by the dashed lines.Thus microwave antenna 104 is converted to a roughly triangular shapethat is suited for endometrial ablation. In FIG. 1L, the distal mostregion of microwave antenna 104 measured along the axis of coaxial cable102 comprises a smooth arc or curve. The microwave antenna 104 in thisembodiment is pre-shaped to form the shape as shown in FIG. 1L. Such amicrowave antenna 104 can be collapsed to enable insertion of microwaveantenna 104 in a collapsed, low-profile, substantially linear,undeployed configuration though a lumen of a device. In FIG. 1L,microwave antenna 104 is sized and shaped such that when it is deployedin the uterine cavity and pushed distally by a user, the distal mostregion of microwave antenna measured along the axis of coaxial cable 102is pushed by the uterine fundus and flattened to achieve theconfiguration as shown by the dashed lines. Thus microwave antenna 104is converted to a roughly triangular shape that is suited forendometrial ablation. In an alternate embodiment, microwave antenna 104has elastic, super-elastic or shape memory ability. In this embodiment,microwave antenna 104 regains its shape after deployment in the uterinecavity through a lumen of a device. Such a microwave antenna 104 may beelastically deformed in the uterine cavity by one or more regions of theuterine cavity. FIG. 1M shows the substantially circular crossection ofmicrowave antenna 104 through plane 1M-1M. FIG. 1N shows two alternatecrossections of microwave antenna 104 through plane 1N-1N. In FIG. 1N,one alternate crossection is rectangular while the other alternatecross-section is oval.

Ablation device 100 may comprise a fluid transport lumen. The fluidtransport lumen extends from a proximal region of ablation device 100till a distal region of ablation device 100 that is placed inside theuterine cavity. The fluid transport lumen may be used for one or moreof: evacuating liquids or gases from the uterus, introducing liquidsinside the uterus such as anesthetics, contrast agents, cauterizingagents, alcohols, thermal cooling agents, a fluid dielectric medium thatsurrounds antenna 104, antibiotics and other drugs, saline and flushingsolutions, introducing gases inside the uterus such as carbon dioxidefor distending the uterine cavity or detecting perforation of theuterus, applying suction to collapse the uterine cavity around theantenna 104. Suction may be applied in the uterine cavity to increasethe contact of antenna 104 with the uterine endometrium. When a gas suchas carbon dioxide is used for distending the uterine cavity and/or fordetecting perforation of the uterus, the gas may be delivered at apressure between 20-200 mmHg.

Ablation device 100 may comprise a device transport lumen. The devicetransport lumen may extend from a proximal region of ablation device 100till a distal region of ablation device 100 that is placed inside theuterine cavity. The device transport lumen may be used for one or moreof: introducing one or more elongate diagnostic and/or therapeuticdevices in the uterine cavity, introducing ablation device 100 over aguidewire or other introducing device and introducing an imaging orvisualization device.

Any of the ablation devices 100 herein may comprise a microwave antennaand/or the positioning devices disclosed in co-pending application nos.:12/ 603,077 filed on Oct. 21, 2009 (attorney docket number MCRCNZ01100);and Ser. No. 12/603,134 filed on Oct. 21, 2009 (attorney docket numberMCRCNZ00500). The entire disclosures of each of which are incorporatedherein by reference.

In one embodiment, a region of outer loop 112 adjacent to the distal endof coaxial cable 102 is electrically shorted to another region of outerloop 112 adjacent to the distal end of coaxial cable 102.

Center loop 114 may be made of Ag or Au plated Nitinol or stainlesssteel. Center loop 114 may or may not be pre-shaped. The crossection ofcenter loop 114 may be circular or rectangular or oval. Center loop 114may be multi-stranded. In one embodiment, center loop 114 is roughlyoval in shape and has a width of 13+/−5 mm and a length of about 35+/−8mm. In one embodiment, center loop 114 is roughly oval in shape and hasa width of 13+/−5 mm and a length of about 27.5+/−8 mm. In oneembodiment, center loop 114 is roughly oval in shape and has a width of13+/−5 mm and a length of about 35+/−8 mm. In one embodiment, ablationdevice 100 further comprises one or more additional elongate metallicconductors or dielectric connected to a region of antenna 104 to confermechanical stability to antenna 104 as well as to shape the microwavefield. Various antennas 104 may be designed using a combination ofvarious elements disclosed herein. Various antennas 104 may be designedusing any combination of a radiating element 112 disclosed herein and ashaping element 114 disclosed herein.

In one embodiment, antenna 104 is mechanically deployable. Antenna 104in this embodiment is user deployable by engaging a mechanicaldeployment system. The mechanical deployment system in one embodiment isa pullable and releasable pull wire attached to a region of outer loop112. Te pull wire may be made of a metallic or non-metallic e.g.polymeric material. When the pull wire is pulled along the proximaldirection, outer loop 112 is distorted. The distortion is such thatantenna 104 achieves a working configuration from an initial non-workingconfiguration. Such an embodiment is advantageous since presence oftissue forces are not required for the proper deployment of antenna.This allows the antenna 104 to be made stiffer. One or more pull wiresmay be attached to one or more regions of antenna 104 to controllablymodify the orientation of antenna 104 relative the axis of the distalend of coaxial cable 102. This may be used to position antenna 104relative to a target tissue in a desired orientation while performinge.g. a laparoscopic procedure. Further, a mechanical deployment systemallows the user to get a feedback (e.g. tactile feedback) about theproper deployment of antenna 104. This eliminates the necessity of apost-deployment visualization of antenna 104 to confirm properdeployment. In another example, the mechanical deployment system allowsthe user to visually observe the extent of displacement of the pull wirewhich is correlated to the extent of deployment of antenna 104.

In a method embodiment, ablation device 100 is introduced in a uterinecavity through an introducing sheath 138. FIG. 3 shows an embodiment ofan ablation system comprising ablation device 100 slidably introducedwithin an introducing sheath 138. The antenna 104 is collapsible suchthat it can be collapsed within a lumen of introducing sheath 138. Thisreduces the overall profile of antenna 104 such that antenna 104 can beintroduced through small openings such as the cervix without needingmuch or any cervical dilation. This significantly reduces the cost anddifficulty of the overall procedure. In one embodiment, ablation device100 is rotatable within a lumen of introducing sheath 138 to change theangular orientation of ablation device 100 relative to introducingsheath 138. In one embodiment, a lumen of introducing sheath 138comprises a sealing or locking mechanism such as a rotating hemostasisvalve to lock the relative rotational and longitudinal positions ofablation device 100 and introducing sheath 138. The distal end ofintroducing sheath 138 may comprise an atraumatic tip. The shaft ofintroducing sheath 138 may be made of a polymeric material. Examples ofpolymeric materials that can be used include, but are not limited toNylon, polyethylene, PEEK, PTFE and silicone. One or more portions ofintroducing sheath 138 may comprise one or more stiffening elements suchas jackets or braids or coatings to increase one or more ofpushability/column strength, kink resistance and torqueability. One ormore portions of introducing sheath 138 may be pre-shaped. Introducingsheath 138 may comprise one or more deflecting or steering elementswhich may be used to deflect or steer antenna 104. Antenna 104 isdeployed by extending the antenna 104 beyond the distal end ofintroducing sheath 138. The outer surface of introducing sheath 138comprises one or more distance markings. Such distance markings areuseful to insert introducing sheath 138 up to a desired depth in theuterine cavity. In one embodiment, the outer surface of the shaft or thetransmission line of ablation device 100 comprises one or more distancemarkings. The one or more distance markings on the shaft of ablationdevice 100 are useful to determine the relative positions of the distalends of the ablation device 100 and introducing sheath 138 within theuterus. In particular, one of the distance markings may be used todetermine if the antenna 104 has been fully deployed out of the distalend of introducing sheath 138. A locking mechanism may be provided tolock the position of ablation device 100 relative to the position ofintroducing sheath 138. In FIG. 3, ablation device 100 comprises anantenna 104. Antenna 104 may be designed using one or more designs orelements disclosed herein. In FIG. 3, antenna 104 comprises a radiatingelement 112 and a shaping element 114. Examples of radiating elements112 include, but are not limited to linear or pre-shaped or bent orcurved monopole antennas and elements similar to outer loop 112 of FIG.1A. Examples of shaping elements include, but are not limited toelements similar to metallic center loop 114 of FIG. 1A and dielectricmaterials. In this embodiment, ablating position 104 is self deployingbecause of its elasticity or shape memory. Ablation device 100 maycomprise one or more pullable or releasable tethers to control theextent of deployment of one or more regions of antenna 104.

FIGS. 2A-2C show the various steps of a method of using an ablationdevice for endometrial ablation. In FIG. 2A, ablation device 100comprises an antenna 104 connected to a transmission line. The proximalend of the transmission line is connected to a proximal handle portion170 that can be manipulated by the user. A second connection 134 isconnected to proximal handle portion. In one embodiment, secondconnection 134 comprises a transmission line that connects antenna 104to a source of energy. Ablation device 100 is slidably enclosed in asubstantially linear, low profile, undeployed, collapsed configurationwithin a lumen of an introducing sheath 138. Antenna 104 can be extendedout of the distal end of the introducing sheath 138 as shown in FIG. 2C.A slidable stopper 130 is located on the outer surface of introducingsheath 138. The position of stopper 130 on sheath 138 can be adjusted bythe user. A proximal region of sheath 138 comprises a distal handlepotion 171 that cooperates with the proximal handle portion 170 tochange the relative positions of ablation device 100 and sheath 138. Inthe embodiment shown, both proximal handle portion 170 and distal handleportion 171 can be operated by a user with a single hand. A lumen ofsheath 138 is in fluid connection with a port that forms a firstconnection 132. First connection 132 may be connected to any externalmodality disclosed herein. In one embodiment, first connection 132 isdesigned to connect to a source of suction. Thus the user can applysuction inside the uterine cavity using the combination of ablationdevice 100 and sheath 138. In one method embodiment, the uterine cavitylength is measured. Thereafter, the position of stopper 130 on sheath138 is adjusted based on the uterine cavity length. Thereafter, sheath138 containing ablation device 100 is introduced inside the uterinecavity until shopper 130 touches the cervix as shown in FIG. 2B. Stopper130 enables the distal end of sheath to be positioned at a desired depthinside the uterine cavity. Stopper 130 may also act as a seal to createa fluid tight seal in the cervix. In FIG. 2C, proximal handle portion170 and distal handle portion 171 are brought together such that antenna104 is deployed inside the uterine cavity. This causes antenna 104 toemerge out of the distal end of sheath 138 and be positioned inside theuterine cavity in a substantially planar, deployed, un-collapsedconfiguration. In one embodiment, the distance by which proximal handleportion 170 and distal handle portion 171 are brought together is basedon a uterine cavity dimension. Thereafter, energy such as microwaveenergy is delivered to the endometrium for ablating the endometrium.Thereafter, proximal handle portion 170 and distal handle portion 171are moved apart such that antenna 104 is enclosed inside sheath 138.Thereafter, sheath 138 and ablation device 100 are removed from theanatomy.

In FIG. 3, the ablation system comprising ablation device 100 introducedwithin an introducing sheath 138 is connected to an external system byone or more connections. Examples of such connections include, but arenot limited to a first connection 132 to a source of suction (e.g. asuction line), a second connection 134 to a source of microwave energy(e.g. a microwave generator) and a third connection 136 to an infusiondevice (e.g. a syringe). In one embodiment, the microwave generator hasan interface to enable the user to adjust the microwave power deliveredto ablation device 100. For example, the microwave power may beadjustable in increments of 5 W (5 W, 10 W, 15 W, etc). In oneembodiment, the microwave generator has an interface to enable the userto adjust the duration of microwave power delivery to ablation device100. For example, the direction of microwave power delivery may beadjustable in increments of 5 s (5 s, 10 s, 15 s, etc). An embodiment ofthe microwave generator designed for the various studies disclosedherein was compact and weighed about 30 pounds. Thus the entire ablationsystem is portable. It can easily be used in the office setting or anoperating room (OR) setting as desired.

Introducing sheath 138 may comprise a fluid transport lumen 140. Thefluid transport lumen 140 may extend from a proximal region ofintroducing sheath 138 till a distal region of introducing sheath 138that is placed inside the uterine cavity. The fluid transport lumen 140may be used for one or more of: evacuating liquids or gases from theuterus, introducing liquids inside the uterus such as anesthetics,contrast agents, cauterizing agents, antibiotics and other drugs, salineand flushing solutions, introducing gases inside the uterus such ascarbon dioxide for distending the uterine cavity or detectingperforation of the uterus and applying suction to collapse the uterinecavity around the antenna 104. Suction may be applied in the uterinecavity to increase the contact of antenna 104 with the uterineendometrium. When a gas such as carbon dioxide is used distending theuterine cavity and/or detecting perforation of the uterus, the gas maybe delivered at a pressure between 20-200 mmHg.

Introducing sheath 138 may comprise a device transport lumen. The devicetransport lumen may extend from a proximal region of introducing sheath138 till a distal region of introducing sheath 138 that is placed insidethe uterine cavity. The device transport lumen may be used for one ormore of: introducing one or more elongate diagnostic and/or therapeuticdevices in the uterine cavity, introducing ablation device 100 over aguidewire or similar introducing device and introducing an imaging orvisualization device.

In one method embodiment, a uterine sound is used to sound the uterus toobtain information about the depth and the position of the uterinecavity and the depth and the position of the cervical canal. Thereafter,ablation device 100 located within introducing sheath 138 is introducedinto the uterine cavity. Antenna 104 is completely within a lumen ofintroducing sheath 138 to reduce the profile of antenna 104. Introducingsheath 138 is navigated within the uterine cavity such that the distalend of introducing sheath 138 touches or is substantially adjacent tothe fundus of the uterus. Thereafter, antenna 104 is deployed within theuterine cavity by withdrawing introducing sheath 138 while maintainingthe position of ablation device 100. In absence of external forces onantenna 104, antenna 104 re-establishes its original shape due to theelastic and/or super-elastic nature of one or more regions of antenna104. Thereafter, ablation device 100 is used to ablate the uterineendometrium. Thereafter, ablation device 100 is removed from the uterus.In one embodiment, this is done by withdrawing ablation device 100proximally while maintaining the position of introducing sheath 138 tocollapse the antenna 104 inside introducing sheath 138. In an alternateembodiment, ablation device 100 is pulled proximally to collapse antenna104 against the cervical canal and the cervix and thereafter removedfrom the uterus.

In one embodiment, a space or gap between the outer surface of ablationdevice 100 and a lumen of introducing sheath 138 acts as a fluid and/ordevice transport lumen.

Ablation device 100 and/or introducing sheath 138 may comprise a stopper130 located on the outer surface of ablation device 100 and/orintroducing sheath 138. Stopper 130 is designed to abut against theexternal portion of the cervix and thereby limit the insertion depth ofablation device 100 and/or introducing sheath 138. The position ofstopper 130 relative to the position of the shaft of ablation device 100and/or introducing sheath 138 may be adjustable. The position of stopper130 relative to the position of the shaft of ablation device 100 and/orintroducing sheath 138 may be reversibly lockable. In one methodembodiment, the desired depth of insertion of ablation device 100 and/orintroducing sheath 138 is determined by one or more of uterine sounding,hysteroscopy and ultrasonography. Thereafter, the position of stopper130 relative to the distal end of ablation device 100 and/or introducingsheath 138 is adjusted. Thereafter, ablation device 100 is inserted intothe uterine cavity. Stopper 130 limits the depth of insertion of thedistal end of ablation device 100 and/or introducing sheath 138 therebyreducing the risk of uterine perforation and ensuring optimal placementof antenna 100 relative to the target tissue. Stopper 130 may also actas an external seal to create a fluid tight seal of the cervical canal.In the embodiment in FIG. 3, ablation device 100 comprises an insertionlimiting feature such as stopper 130 to limit the insertion depth ofablation device 100.

In another embodiment, ablation device 100 comprises an antenna 104 thatcomprises a non-linear radiating element 112 and a non-linear shapingelement 114. In this embodiment, both radiating element 112 and shapingelement 114 are each connected to separate tethers. The tethers can bemanipulated by the user to change the shape and/or orientation of one ormore of: radiating element 112 and shaping element 114 in the anatomy.In this embodiment, radiating element 112 may be made of a length of aconductor coated with a dielectric material. Shaping element 114 may bemade of multiple strands of outer conductor 106 that are twistedtogether.

FIG. 4 illustrates the key steps of an embodiment of a method ofendometrial ablation. At step 100A, the patient is screened to determineif she is suitable for ablation. This may include one or more of takingmedical history, ultrasonography (with or without saline infusion),endometrial biopsy and asking the patient her treatment preferences. Atstep 102A, uterine dimensions are measured. The uterine dimensionsmeasured may be selected from the group comprising: uterine cavitylength and/or width, uterine cavity position, uterine cavityorientation, cervical canal length and/or width and cervical canalposition. This may be done by one or more of A. ultrasonography(abdominal or trans-vaginal) with or without contrast agent or saline inthe endometrial cavity, B. pre-procedure MRI with or without a contrastagent or saline in the endometrial cavity, C. sounding the uterus by astandard uterine sound or a Wing Sound-like device that not justmeasures the uterine cavity and cervical cavity length, but also theuterine cavity width in the cornual region and D. performing a bimanualexamination or palpating the uterus to get an idea of the approximatedimensions and the orientation. At step 104, the patient is prepped forthe procedure. The patient may be positioned in the standard positionused for gynecological examination such as the dorsal lithotomy positionusing stirrups. The patient may be draped. The patient is advised aboutwhat to expect during and after the procedure. A speculum may beinserted. The cervix may be grasped with a tenaculum if necessary. Atstep 106A, anesthesia if needed is administered to the patient. In oneembodiment, oral pain medications e.g. NSAIDs are given a few hoursbefore the procedure. At step 106A, a para-cervical block is placed.Since this procedure requires minimal anesthesia, it may easily be donein the office. The slim and flexible nature of several embodiments ofantennas 104 disclosed herein may allow the physician to perform anablation without any anesthesia. If the patient wishes, the proceduremay be carried out in an ambulatory surgical center or in an operatingroom. Also, the physician may decide to in an ambulatory surgical centeror in an operating room. For example, if the patient is morbidly obese,then the physician may decide to perform the procedure in an OR. Thus,in step 106A, conscious sedation or general anesthesia may beadministered. Slight cervical dilation if necessary may be done afterstep 106A. In step 108A, ablation device 100 is opened from its package.In one embodiment, various ablation devices 100 of varying sizes andshapes are provided. For example, a set of three ablation devices 100may be provided wherein each ablation device 100 is adapted to treat auterus lying within a particular size and shape range. The user may usethe uterine dimension data from step 102A to select the appropriateablation device 100 for the ablation. Alternately, a single ablationdevice 100 is designed to be usable for all patients. At step 110A,ablation device 100 is tailored to the anatomy. In one embodiment, oneor more of ablation 100 device size and shape parameters may be changedby the physician to tailor ablation device 100 to the patient's anatomy.For example, a deployed length and/or width of ablation device 100 maybe changed. The ablation device 100 may be tailored to account for oneor more of: uterine cavity length and/or width, uterine cavity position,uterine cavity orientation, cervical canal length and/or width andcervical canal position. In one embodiment, the position of stopper 130is adjusted on the shaft of ablation device 100. At step 112A, ablationdevice 100 is inserted trans-cervically into the uterine cavity. Theablation device 100 is positioned such that antenna 104 is locatedwithin the uterine cavity. In one embodiment, ablation device 100 isinserted in a collapsed configuration for insertion through a narrowopening (e.g. <4 mm in diameter). When the distal region of ablationdevice 100 reaches the target location, antenna 104 is un-collapsed ordeployed in the working configuration. In step 114, the criticalpre-ablation parameters needed for the safety and efficacy of theprocedure are verified. For example, placement of antenna 104 in theuterine cavity may be confirmed. The placement and/or the orientation ofantenna 104 may be verified by imaging or by accurately calculating theposition and/or the orientation of the device. A perforation detectiontest may be performed to rule out ablation device-caused ornaturally-present perforations of the uterus. This test may be carriedout by detecting leaks of a fluid introduced into the uterine cavity.The proper contact of antenna 104 with the surface of the endometriummay be determined by imaging (e.g. ultrasound imaging) or other methodsuch as measuring a physical parameter such as the temperature orimpedance of adjoining tissue. In one embodiment, a vaginoscopictechnique is used to insert ablation device 100 into the anatomy. In avaginoscopic technique, a type of endoscope is used to visualize thevaginal canal. In this technique, a speculum is not used. Further, inthis technique, a tenaculum may not be needed to grasp the cervix. Atstep 116A, the endometrium is ablated. The ablation parameters may beautomatically selected by the microwave generator after the user enterssome patient specific data such as anatomical data. Alternately, theuser may calculate the ablation parameters such as the magnitude ofpower delivery, waveform, ablation time, etc. based on specific inputssuch as patient's anatomical data. The ablation parameters may then befed into the generator. The end point of the ablation may be determinedautomatically by the microwave generator or the user may decide anablation endpoint based on a protocol. One or more parameters may beused to calculate the end point and/or terminate the ablation. Examplesof such parameters include, but are not limited to tissue temperature atone or more places, ablation time, ablation power, impedance of tissueat one or more places, patient's anatomical parameters, etc.

In step 118A, after the ablation is finished, the antenna 104 iscollapsed and removed from the uterus. Thereafter, in step 120A, thepatient is followed up post-procedure for a certain time. The patientmay be given specific instructions on the symptoms of some ablationcomplications so that the patient can contact the physician immediatelyif she experiences those symptoms post-procedure.

It is not necessary that all of the abovementioned steps are performedduring the method. One or more steps may be added, deleted or modifiedas per the clinical requirements.

Instead of ablation, the method and devices herein may be used for otherapplications as disclosed elsewhere. The procedures disclosed herein maybe performed under real-time monitoring e.g. by direct visualization,hysteroscopy, ultrasound, radiologically, by laparoscope, etc.

FIGS. 5A-5E illustrate the key steps of ablating uterine endometrium totreat menorrhagia using a collapsible microwave ablation antenna.Although only a few key steps are illustrated in FIGS. 5A-5E, it isemphasized that any other method steps disclosed elsewhere in thespecification may be added to or substituted for a step in FIGS. 5A-5E.In FIG. 5A, ablation device 100 located within introducing sheath 138 isintroduced into the uterine cavity such that the distal end ofintroducing sheath 138 touches or is substantially adjacent to thefundus of the uterus. In one method embodiment, anatomical informationabout uterine cavity and cervical canal lengths and positions areobtained prior to the step in FIG. 5A. This anatomical information isused to position the distal end of introducing sheath 138 in the uterinecavity. Further, in the step shown in FIG. 5A, introducing sheath 138 iswithdrawn in the proximal direction while maintaining the position ofablation device 100. This deploys antenna 104 in the uterine cavity asshown in FIG. 5B. After antenna 104 is deployed in the uterine cavity,ablation device 100 is displaced in the distal direction by a calculatedamount in step 4D. This displacement causes the distal most region ofantenna 104 to be pressed against the uterine fundus. This in turncauses antenna 104 to flatten and achieve a working configuration. Inone embodiment, the amount of displacement of ablation device 100 in thedistal direction is calculated based on an anatomical dimension such asa uterine dimension (e.g. the length of the uterine cavity). Microwaveantenna 104 of antenna 104 is longitudinally compressible similar to theembodiments shown in FIGS. 6A and 6B to achieve a working configuration.Ablation device 100 is placed such that antenna is longitudinallycompressed by the fundus of the uterus and is in the workingconfiguration as shown in FIG. 5C. It should be noted that in theembodiment shown in FIG. 5C, the deployed antenna 104 extends over amajority of (more than half of) the uterine cavity. More specifically,the deployed maximum width of antenna 104 is greater than half of themaximum width of the uterine cavity and more specifically, greater thanthree fourths of the maximum width of the uterine cavity. Also, thedeployed length of antenna 104 is more than half the length of theuterine cavity and more specifically, greater than three fourths of thelength of the uterine cavity. Further, in the step shown in FIG. 5C,ablation device 100 is used to ablate the uterine endometrium.Thereafter, in the step shown in FIG. 5D, introducing sheath 138 isadvanced distally over antenna 104. This collapses antenna 104 andcauses ablation device 100 to be enclosed within introducing sheath 138.Thereafter, in the step shown in FIG. 5E, introducing sheath 138 alongwith ablation device 100 is removed proximally from the anatomy.

It should be noted that the simple design of ablation device 100 reducesthe device cost. Further, such a simple endometrial ablation procedurehas a low total procedure cost. This enables a wide variety ofphysicians in the US and elsewhere to use this technique. This techniquecan easily be used in a physician's office which reduces the procedurecost even more.

Ablation device 100 disclosed herein may be inserted and/or used blindlyi.e. without using any additional imaging modality.

Alternately, ablation device 100 disclosed herein may be inserted and/orused under hysteroscopic guidance. Thus, hysteroscopic microwaveendometrial ablation, if desired, is possible with the various devicesand methods disclosed herein. In one embodiment, a slim diagnostichysteroscope is co-introduced through the cervix along with an ablationdevice 100 into the uterine cavity. The slim diagnostic hysteroscope isthen used to visualize and guide the placement of ablation device 100 inthe uterine cavity. Thereafter, the diagnostic hysteroscope is partiallyor full withdrawn from the anatomy. Thereafter, an ablation procedure isperformed by ablation device 100. In another method embodiment, ablationdevice 100 is introduced in the anatomy through a channel of ahysteroscope or resectoscope sheath. The ablation devices 100 disclosedherein can be made sufficiently low profile to enable their introductionthough a channel (e.g. a 7 French channel) of a hysteroscope orresectoscope sheath. The hysteroscope or resectoscope sheath may bepartially or fully withdrawn from the anatomy before an ablationprocedure by ablation device 100.

Alternately, ablation device 100 disclosed herein may be inserted and/orused under ultrasonic guidance. The ultrasonic guidance may betrans-abdominal ultrasound, trans-vaginal ultrasound or intra-uterineultrasound.

Alternately, ablation device 100 disclosed herein may be inserted and/orused under radiological guidance. In one embodiment, ablation device 100is used under X-ray or fluoroscopic guidance. Ablation device 100 maycomprise one or more radiopaque markers to enable the visualization ofone or more regions of ablation device 100 under X-ray or fluoroscopicguidance.

Alternately, ablation device 100 may comprise a visualization modalityor means for coupling to a visualization modality. In one embodiment,the visualization modality (e.g. fiberoptic fibers or other opticalimaging modality, ultrasound catheter, etc.) may be embedded in a wallof ablation device 100 and/or introducing sheath 138. In anotherembodiment the visualization modality (e.g. fiberoptic fibers or otheroptical imaging modality, ultrasound catheter, etc.) may be introducedthrough a lumen of ablation device 100.

Ablation device 100 may comprise one or more gas or liquid inflatableballoons for doing one or more of positioning antenna 104, providing acooling modality, enabling better contact of antenna 104 with targettissue and deploying antenna 104.

FIG. 6A shows a longitudinally un-constrained and laterally un-collapsedconfiguration of an embodiment of a microwave antenna. In FIG. 6A,ablation device 100 comprises an antenna 104 comprising an outer loop112 and a metallic center loop 114. Outer loop 112 in this configurationis in a more oval shape. The maximum lateral width dimension of antenna104 is about 2.7 cm. The lateral width of center loop 114 is 1.6cm+/−0.6 cm and the longitudinal length of center loop 114 is about 5.5cm+/−1 cm.

FIG. 6B shows a longitudinally constrained and laterally un-collapsedworking configuration of the embodiment of a microwave antenna shown inFIG. 6A. In FIG. 6B, an external force is used to distort the distalmost portion of antenna 104. In FIG. 6B, the distal most portion ofantenna 104 was pressed using a finger to demonstrate the distortion ofthe shape of outer loop 112 from a more oval shape to a more triangularshape as shown. The maximum lateral width dimension of outer loop 112 isnow about 3.5 cm. The longitudinal length of antenna 104 from the distalend of coaxial cable 102 till the distal most portion of antenna 104 isabout 3.8 cm. This simulates the distortion that antenna 104 experiencesby the fundus during actual clinical use in endometrial ablation. Theconfiguration shown in FIG. 6B is the working configuration of antenna104 in which antenna 104 can be used for endometrial ablation. Thusantenna 104 is capable of existing in three configurations: a firstundeployed configuration in which antenna 104 is laterally compressedfor insertion through a lumen or opening, a second deployedconfiguration in which antenna 104 is deployed in the anatomy and islongitudinally un-constrained and laterally un-collapsed in the absenceof significant external distorting forces on antenna 104 and a thirddeployed configuration in which antenna 104 is longitudinallyconstrained and laterally un-collapsed in the presence of externaldistorting forces on antenna 104. The third configuration is the actualworking configuration.

FIG. 6C shows the placement of the microwave antenna of FIGS. 6A and 6Bin a folded piece of tissue. In FIG. 6C, a slab of porcine muscle tissuemaintained at 37 degrees C. was folded over once. The cavity enclosed bythe tissue fold approximately simulates the uterine cavity. Thereafter,antenna 104 of FIGS. 6A and 6B was inserted to a sufficient depth suchthat the distal most region of antenna 104 is distorted by the porcinetissue to achieve the working configuration as shown in FIG. 6B.Thereafter, the porcine tissue was ablated. The time of power deliverywas less than two minutes. Thus endometrial ablation protocols may bedesigned that ablate a sufficient amount of endometrium in less than towminutes. In Figs. 6A and 6B, the ablation was done for 90 s with adelivery of 40 W of microwave power from a microwave generator at 0.915GHz. Although in this experiment, a constant power of 40 W was usedthroughout the ablation procedure; in clinical use the magnitude ofpower delivery by the microwave generator may not be constant throughoutthe ablation procedure.

In one embodiment, the magnitude of power delivered by ablation device100 is varied with time during an ablation. In one such embodiment, ahigher power is delivered during the first stage of the ablation.Thereafter, the power delivery in the subsequent stages of the ablationis lowered. In one embodiment, the power delivery in the subsequentstages of the ablation is lowered when tissue temperature reaches adesired level e.g. 80 C. In this embodiment, the power delivery may belowered to maintain the tissue temperature at or below the desired levelfor a desired time. The power delivery may also be lowered to maintainthe temperature of the uterine serosa at or below a desired safe limitduring the ablation. In another embodiment, the power delivery in thesubsequent stages of the ablation is lowered after a specified time. Inone embodiment, the microwave generator is capable of automaticallyadjusting the magnitude of power delivery based on one or more of: (i) apre-programmed therapy cycle and (ii) a feedback obtained during theablation. Examples of pre-programmed therapy cycles include, but are notlimited to: a 50% on −50% off duty cycle; a 70% on −30% off duty cycleand cycles wherein the magnitude of power delivery is varied with time.The relative proportion of the on-time and off-time during a duty cyclemay be varied though the ablation. The on-time and off-time of a dutycycle may be synchronized with one or more of pulsatile blood flow and acooling modality. Examples of parameters that can be used for feedbackduring the procedure include, but are not limited to: temperature,impedance, blood flow, tissue viability, tissue electrical signals (e.g.EKG, EEG, etc.) and tissue characteristics.

In any of the methods disclosed herein, the water content of tissuevolume or a surface may be locally modified e.g. by injecting orintroducing an aqueous solution. The aqueous solution may be heated updue to absorption of microwave energy. The heated aqueous solution thenacts as an additional ablating modality. The heated aqueous solution mayflow and conform to irregular regions of target tissue and thuscomplement the abative action of antenna 104.

If we assume that about 85% of the total microwave energy delivered bythe microwave generator is ultimately delivered by antenna 104 totissue, the total energy delivered to tissue is about 3,000 Joules.Since the tissue used in FIG. 6C is designed to simulate uterineendometrial tissue, endometrial ablation protocols may be designed thatinvolve the delivery of about 3,000 Joules of microwave energy to theendometrium. Further, protocols of endometrial ablation may be designedthat deliver less than 3,000 Joules of microwave energy to theendometrium. This can be done for example, by pre-treatment of theuterus, by scheduling the patient for the ablation just after she has amenstrual period, etc.

In FIG. 6B, the total area of generally flattened antenna 104 in itsworking configuration is about 6.7 square centimeters. Thus, themicrowave energy delivered by antenna 104 is delivered to two oppositetissue surfaces, each measuring about 6.7 square centimeters. Again, ifwe assume that about 85% of the total microwave energy delivered by themicrowave generator is ultimately delivered by antenna 104 to tissue,the total power delivered to tissue is about 2.5 Watts per squarecentimeter of tissue. Further, protocols of endometrial ablation may bedesigned that achieve the desired clinical outcome while delivering lessthan 2.5 Watts of microwave power per square centimeter of endometrialsurface. This can be done for example, by hormonal pre-treatment of theuterus, by a mechanical pre-treatment of the uterus by D&C, byscheduling the patient for the ablation just after she has a menstrualperiod, etc.

FIG. 6D shows the unfolded piece of tissue of FIG. 6C showing theplacement of the microwave antenna of FIGS. 6A and 6B in alongitudinally constrained and longitudinally collapsed workingconfiguration and the ablation obtained from the microwave antenna. Itshould be noted that the ablation is roughly triangular in shape. Suchan ablation in the uterus is capable of ablating the entire uterineendometrium to treat menorrhagia without the need of repositioningantenna 104.

FIG. 6E shows an unfolded view of ablated tissue after the ablationshown in FIG. 6C. FIG. 6F shows a view of the ablated tissue slicedthrough the plane 6F-6F in FIG. 6E. It is seen in FIG. 6F, that theablation is uniform and spans the full thickness of the tissue. There isno charring noted anywhere. Thus a transmural ablation spanning the full7-9 mm depth of tissue has been created. FIG. 6G shows a view of theablated tissue sliced through the plane 6G-6G in FIG. 6E. Similar toFIG. 6F, FIG. 6G shows that the ablation is uniform and spans the fullthickness of the tissue. There is no charring noted anywhere. Thus atransmural ablation spanning the full 7-10 mm depth of tissue has beencreated. Further, it should be noted that the lesion is deeper in thecenter and shallower towards the periphery of the lesion. Such anablation is clinically desired since the thickness of the endometrium isgreater toward the center of the uterus and is lower in the cornualregions and towards the lower uterine region. Further, deeper lesionsmay be created if desired by using one or more of: increasing the powerdelivered by the microwave generator, increasing the ablation time,occluding the blood flow to the uterus by temporarily occluding theuterine arteries, etc. Further, shallower lesions may be created ifdesired by using one or more of: reducing the power delivered by themicrowave generator, reducing the ablation time, using a coolingmodality such as a circulating cooling agent in the anatomy, etc. Acooling modality may be used to cool the surface of the endometrium.

Further, such a deep ablation of tissue enables ablation device 100 tobe used for endometrial ablation without any pre-treatment of theendometrium. Several of the prior art endometrial ablation techniquesrequire pre-treatment of the endometrium to thin the endometrium. Forexample, Dilatation & Curettage (D&C) or hormonal pre-treatment isnecessary before using several of the prior art techniques. This drivesup the overall cost and complexity of the treatment process. Further,hormonal pre-treatment is not readily accepted by the patients becauseof the potential for unpleasant side effects. The deep lesion created bythe devices and methods disclosed herein may easily be used forendometrial ablation without needing any pre-treatment. Further, such adeep ablation of tissue enables the devices and methods disclosed hereinto be used at any time during the menstrual cycle.

The maximum tissue temperature measured during the ablation was 85degrees C. Thus, there is no risk of charring of tissue. Further, thiseliminates the formation of steam during the ablation. This in turneliminates the medical risks due to steam formation. Steam generatedduring the ablation dissipates heat and also carries the risk of burninghealthy tissue. It should also be noted that antenna 104 did not stickor adhere to the tissue. This is critical since ablation device 100 willhave none or minimal risk of sticking to uterine tissue when used forendometrial ablation.

One or more of the endometrial ablation methods disclosed herein may becombined with occlusion of uterine arteries to increase the efficacyand/or increase the safety of the endometrial ablation methods. One ofthe factors that reduce the efficacy of some existing endometrialablation techniques is blood flow in the uterus. The blood flow acts asa heat sink and carries away the heat delivered to the uterus. Thus, ifa thermal endometrial ablation method is performed while reducing theuterine blood flow; a beneficial effect may be obtained. FIGS. 7A and 7Billustrate two steps of a method of endometrial ablation with a reduceduterine blood flow. In FIGS. 7A and 7B, uterine arteries 142 areoccluded. The occlusion is temporary and is created by a clamp 144 thatis inserted through the vagina and is used to compress the externalsurface of the cervix to compress and occlude the uterine arteries 142.Alternately, a permanent occlusion of the uterine arteries 142 may beused. The uterine artery occlusion may be partial or complete. In oneembodiment, the location of the uterine arteries 142 and/or themagnitude of the blood flow in the uterine arteries is determined byusing Doppler ultrasound or other ultrasound modality. Similarendometrial ablation methods are contemplated that use an existingendometrial ablation modality such as hot liquid balloons, freecirculating hot liquids, etc. in conjunction with temporary or permanentuterine artery occlusion. In such endometrial ablation methods, theamount of thermal energy delivered to the endometrium may be reduced ascompared to similar endometrial ablation methods that do not use uterineartery occlusion. Treatment protocols may be designed that deliver alower amount of thermal energy to the uterine. Alternately, the amountof thermal energy delivered to the endometrium may be kept the same.

Although several embodiments of ablation devices 100 have been disclosedherein that are capable of ablating the entire anatomical target in asingle ablation without repositioning antenna 104, several device andmethod embodiments are envisioned wherein antenna 104 is re-positionedat least once to ablate multiple locations in the anatomical target. Forexample, endometrial ablation methods may be designed wherein antenna104 is positioned at a first location in the uterine cavity and is usedto ablate the first location in the uterine cavity. Thereafter, antenna104 is positioned at a second location in the uterine cavity and is usedto ablate the second location in the uterine cavity. Thereafter, ifneeded, antenna 104 may be repositioned at additional locations in theuterine cavity and used to ablate the additional locations in theuterine cavity. FIGS. 8A-8C show the steps of a method of using anablation device 100 with a deflectable or steerable antenna 104 beingused for endometrial ablation. In FIG. 8A, an ablation device 100comprising antenna 104 is introduced trans-cervially into the uterinecavity. Although in the embodiment shown in FIG. 8A, antenna 104comprises a radiating element 112 (e.g. a monopole antenna, a helicalantenna, outer loop 112 of FIG. 1, etc.) without any shaping element,one or more conducting or non-conducting shaping elements 114 may beadded to antenna 104 to shape the microwave field. In the embodiment inFIG. 8A, the length of antenna 104 is greater than half of the uterinecavity length. Antenna 104 is positioned such that the distal end ofantenna 104 is in the vicinity of the uterine fundus. In FIG. 8A,antenna 104 is used to ablate a region of the uterine endometrium.Thereafter, in FIG. 8B, antenna 104 is moved to a different location inthe uterus and antenna 104 is used to ablate a region of the uterineendometrium. In one embodiment, a deflecting or steering mechanism onablation device 100 is used to displace antenna 104. Examples of suchdeflecting or steering mechanisms include, but are not limited to: pullwires, balloons and magnetic steering. The steering mechanisms such aspull wires may be designed such that there is none or minimalinteraction of the steering mechanisms with the microwave field. In oneembodiment, the deflecting or steering mechanisms are made ofnon-conductive materials. Thereafter, in FIG. 8C, antenna 104 is movedto another location in the uterus and antenna 104 is used to ablate aregion of the uterine endometrium. Similar to the step in FIG. 8B, adeflecting or steering mechanism on ablation device 100 may be used todisplace antenna 104. The ablations created in the steps in FIGS. 8A, 8Band 8C may be overlapping or non-overlapping. The ablations created inthe steps in FIGS. 8A, 8B and 8C may be shaped to be wider distally andnarrower proximally in the uterine cavity. In one alternate embodiment,the ablations created in the steps in FIGS. 8A, 8B and 8C may have asubstantially constant width along their length. Antenna 104 in FIGS.8A, 8B and 8C may be substantially flexible or substantiallynon-flexible. The displacement of antenna 104 may be performed by acontroller coupled to a proximal portion of ablation device 100. Thecontroller may be mechanical and/or electromechanical.

Antenna 104 may be repositioned at multiple regions in the target tissuewith or without using a deflecting or steering mechanism on ablationdevice 100 to ablate a larger region of the target tissue. A physiciancontrolled movement of the ablation device 100 may be used to repositionantenna 104. Two or more ablations may thus be created that may or maynot overlap with each other. For example, FIGS. 8D-8E show a methodembodiment of treating a uterine cavity by ablating a distal and aproximal region of the uterine cavity in two separate ablations. Suchmethods may be used for treating a uterus with a normal cavity or alarge uterus (e.g. having a uterine cavity of >8 cm in length). Suchmethods also allow the use of a smaller antenna 104 that can berepositioned one or more times to ablate a larger region of targettissue. In FIG. 8D, antenna 104 is used to ablate a distal region in theuterine cavity. In one device embodiment, center loop 114 is stifferthan outer loop 112. Ablation device 100 is advanced into the uterinecavity such that the distal region of outer loop 112 touches the fundusand is distorted by the fundus as shown in FIG. 8D. Ablation device 100is further advanced into the uterine cavity such that the distal regionof center loop 114 touches a portion of the uterine cavity. The userfeels the increased resistance and stops advancing ablation device 100further into the uterine cavity. Thus, the user gets a tactile feedbackabout the accurate positioning of antenna 104 inside the uterine cavity.In another embodiment, a stopper located on either of introducing sheath138 or coaxial cable 102 is used to position antenna 104 accurately inthe uterine cavity. The stopper may be designed such that it abutsagainst the external region of the cervix and prevents furtheradvancement of ablation device 100. The location of the stopper alongablation device 100 may be adjustable. The location of the stopper alongablation device 100 may be adjusted based on anatomical data obtainedbefore the ablation. Thereafter, in FIG. 8E, antenna 104 is repositionedto a proximal location in the uterine cavity. Thereafter, a secondablation is carried out. Thus, several ablation protocols may bedesigned that direct the user to place antenna at pre-specifiedlocations in the uterine cavity. These protocols may be based on one ormore of: tactile feedback, pre-procedure imaging, anatomical dimensions(length and position of the uterine cavity, length and position of thecervical canal, width of the uterine cavity, uterine cavity shape, etc.)obtained before an ablation, intra-procedure imaging, location ofanatomical landmarks, location of device landmarks and intra-procedurefeedback (e.g. temperature feedback, impedance feedback). Such protocolsdiffer from prior art endometrial ablation protocols such as MicrowaveEndometrial Ablation of Microsulis Medical Ltd. that are based solely ontemperature feedback. The methods herein may be used to ablate theentire or a part of (e.g. about 50% or about 75%) the endometrium. Themethods herein may be used to increase procedural safety e.g. bypreventing any ablation of the cervical canal. The shapes of antenna 104in FIGS. 8D and 8E may or may not be the same because of differingdistortions to antenna 104 by the anatomy. Any of the antennas 104disclosed herein may be repositioned by one or more of: rotating aroundan axis, moving proximally or distally, moving sideways, revolvingaround an axis, increasing or reducing in size, engaging a steering ordeflecting mechanism on ablation device 100 and engaging a steering ordeflecting mechanism on an accessory device. Further, any of theantennas 104 disclosed herein may be designed and used such that duringclinical use the forces exerted by a flexible antenna 104 on the uterinewall do not distort the uterine cavity.

Multiple antennas 104 located on one or more ablation devices 100 may beused to ablate one or more regions of the anatomy. For example, FIG. 9shows a method of simultaneously using two ablation devices 100 toablate the uterine endometrium. In this embodiment, two ablation devices100 each comprising a single antenna 104 are used to ablate the uterineendometrium. Alternately, more than two ablation devices 100 may be usedto ablate the uterine endometrium. The ablation devices 100 in FIG. 9may comprise a deflecting or steering mechanism to displace antenna 104.The ablations created by ablation devices 100 in FIG. 9 may beoverlapping or non-overlapping. The ablations created by ablationdevices 100 in FIG. 9 may be created simultaneously or sequentially.Ablation devices 100 in FIG. 9 may be supplied by a single energy sourcee.g. a single generator or multiple energy sources e.g. multiplegenerators. In other embodiments, an ablation device 100 comprising twoor three or more antennas 104 is used to ablate a target tissue.

One or more devices disclosed herein may comprise one or more ultrasoundimageable and/or radiopaque components. One or more devices disclosedherein may comprise one or more lubricious coatings. One or more devicesdisclosed herein may comprise one or more regions that are thermallyinsulated to protect non-target tissue. One or more devices disclosedherein may comprise a torqueable shaft and a proximal orientationmarker. For example, ablation device 100 may comprise a torqueable shaftand a proximal hub with wings. The user can thus determine theorientation of the antenna 104 within the body by knowing theorientation of the wings of the proximal hub that lie outside the body.

FIGS. 10A and 10B show two methods of using a trans-cervical accessdevice in combination with a energy emitting device to treat a localregion of the uterus. In FIGS. 10A and 10B, an access device is used tocreate an access to the uterine cavity. Thereafter, a working devicee.g. an ablation device 100 is inserted inside the uterine cavity usingthe access device. Thereafter, the working device is used to perform adiagnostic or therapeutic procedure on one or more regions of theuterus. In FIG. 10A, the access device is a hysteroscope sheath 173comprising a device lumen 174. A hysteroscope 172 enclosed withinhysteroscope sheath 173 is introduced inside the uterine cavity.Hysteroscope 172 may be used to guide the introduction and placement ofthe working device such as an ablation device 100. The cervix may thenbe sealed to create a fluid tight seal to enable a distension medium tobe used to distend the uterine cavity. In one device embodiment, theaccess device e.g. hysteroscope sheath 173 has one or more openings onits surface that are positioned in the cervical canal. Thereafter,suction applied through the one or more openings collapses the cervicalcanal tissue over the access device thereby sealing the cervix. In FIG.10A, the working device is an ablation device 100 designed for ablatingportions of the uterine wall. After ablation device 100 is insertedinside the uterine cavity, antenna 104 of ablation device 100 may bedeployed and positioned adjacent to the target tissue. A shield 176 maybe positioned outside the uterus to protect abdominal organs from theenergy delivered by ablation device 100. The access device and/orworking device may be used to generate a vacuum in the uterine cavity toremove any gases, debris, moisture, etc. The access device and/orworking device may be used to deliver local anesthetic inside theuterine cavity. Ablation device 100 may be used to ablate one or moreregions of the uterine wall to treat local lesions such as adenomyosis,polyps, uterine cancer, hyperplasia, etc or to globally ablate theendometrium. A chemical or mechanical pre-treatment of a uterine regionmay be performed before a procedure. After the procedure is complete, anintervention to prevent adhesions in the uterine cavity may be performede.g. by inserting a packing material. Thereafter, the working device andaccess device are removed from the anatomy. FIG. 10B shows a variationof the method of FIG. 10A wherein antenna 104 is used to treat asub-mucous fibroid. In one embodiment, the entire volume of the fibroidis treated. In another embodiment, the endometrium covering the fibroidis treated.

Even though antenna 104 is designed to work well without exact contactwith tissue, there may be an advantage if the proper positioning of theantenna 104 is determined just before the ablation. The invention hereinfurther includes a non-visual and integrated device that can be used todetermine the proper positioning of antenna 104 just before theablation. The method uses reflectometry to determine the properpositioning. If the antenna is not properly positioned, the antenna maynot be well matched. In such a case, the measured reflected power for aparticular range of incident power (the power sent to the antenna) willnot be within a normal range. Thus by measuring if the reflected poweris within a normal range, we can say whether the antenna is properlypositioned. An example of such a procedure is as follows. 1. Conduct aseries of experiments with the antenna properly positioned in the targettissue, 2. Measure the reflected power level in all the experiments fora particular range of incident power level with the antenna properlypositioned in the target tissue, 3. Determine a “normal range” ofreflected power level that is to be expected if the antenna is properlypositioned in the target tissue, 4. During the endometrial ablationprocedure, measure the reflected power level, 5. If the reflected powerlevel is within the normal range, conclude that the antenna is properlypositioned. If the reflected power level is not within the normal range,conclude that the antenna is not properly positioned. As an optionalextra step, a series of experiments may be conducted with the antennaimproperly positioned in the target tissue by having the antennadeployed purposely in imperfect or wrong configuration. This is todetermine an “abnormal range” of incident power level that is to beexpected if the antenna is not properly positioned in the target tissue.

The reflected power level can be measured by 1. using an external powermeter or 2. using a power meter that is in-built within the microwavegenerator.

The devices and methods disclosed herein may also be used to treatDysmenorrhea. Reduction in Dysmenorrhea has been clinically documentedafter endometrial ablation. In one method embodiment, one or more of themethods and devices disclosed herein may be used to treat concomitantDysmenorrhea and menorrhagia.

The microwave field generated by any antenna 104 disclosed herein may bedirected towards a particular direction by a variety of mechanisms. Forexample, a microwave reflector (e.g. a metallic mesh) may be positionedon one side of a flat or planar ablation portion to reflect themicrowave energy to the other side of the flat or planar ablationportion. One or more microwave absorbing or shielding or reflectingmaterials may be used in combination with the embodiments disclosedherein to direct the microwave field to a particular direction. In oneembodiment, the whole or part of center loop 114 is designed to act as amicrowave shield or reflector or absorber.

Some of the embodiment of ablation device 100 such as in FIG. 1A may bebroadly described as microwave devices comprising a coaxial cable and anantenna at the distal end of the coaxial cable. The antenna comprises aradiating element that extends from the distal end of the coaxial cable.For example, the radiating element may be a continuation of the innerconductor of the coaxial cable or may be an additional element connectedto the inner conductor of the coaxial cable. The radiating elementradiates a microwave field that is characteristic of its specificdesign. The radiated microwave field causes agitation of polarizedmolecules, such as water molecules, that are within target tissue. Thisagitation of polarized molecules generates frictional heat, which inturn raises the temperature of the target tissue. Further, the microwavefield radiated by the radiating element may be shaped by one or moreshaping element(s) in the antenna. The shaping element(s) may beelectrically connected to the outer conductor of the coaxial cable.Several embodiments of the radiating element and the shaping element andcombinations thereof are described herein. A significant portion of thedisclosure discloses embodiments of ablation devices, wherein theradiating element is substantially a loop and the shaping element issubstantially a loop. Although a significant portion of the disclosurediscloses such embodiments of ablation devices, the invention alsoincludes other embodiments of ablation devices and methods of using suchdevices. For example, one or both of outer loop 112 and center loop 114may be replaced by one or more non-looped conducting, non-conducting orinsulated elements. Examples of such elements include, but are notlimited to: straight or curved segments of metallic elements, elementswith a circular or oval shape, elements with a polygonal shape (e.g.triangular, square, rectangular, pentagonal, etc.), multiple elementsjoined together by an electrically conducting joint(s), multipleelements joined together by a non-electrically conducting joint(s),elements with multiple curves, symmetrically arranged segments ofelements, non-symmetrically arranged segments of elements, segments ofnon-conducting materials, etc.

Several embodiments of antennas 104 may be designed to have single ormultiple splines, curves or loops in a generally planar arrangement.This is advantageous in ablating a surface such as the surface of organssuch as liver, stomach, esophagus, etc.

Devices disclosed herein may be constructed with various orientations ofthe antenna 104 relative to the region of coaxial cable 102 immediatelyproximal to antenna 104. Devices herein may be designed with a planarantenna 104 that is substantially parallel to the region of coaxialcable 102 immediately proximal to antenna 104. Devices can also bedesigned with a planar antenna 104 oriented at an angle (e.g. 90+/−20degrees, 45+/−20 degrees) to the region of coaxial cable 102 immediatelyproximal to antenna 104. This is advantageous to reach hard-to-reachtarget regions in the body. The relative orientation of whole orportions of antenna 104 relative to the device shaft (e.g. the coaxialcable 102) may be fixed or changeable. For example, there may be aspringy joint or region between antenna 104 and the shaft. In anotherembodiment, there may be an active steering mechanism e.g. a pull wiremechanism to change the relative orientation of whole or portions ofantenna 104 relative to the shaft. Such mechanisms may be used forproper positioning of antenna 104 on the target tissue or for navigatingthe device through the anatomy. For example, an antenna 104 deployedthrough an endoscope or through a laparoscope port may be deployed andnavigated such that antenna 104 lies in the plane of the target tissue.

The user may be supplied several devices of varying size and/or shape.The user may then select the proper device based on his judgment tocarry out the ablation. In a particular embodiment, 2 to 3 differentdevices with antennas 104 of similarly shape but different sizes aresupplied. The user then selects the proper device. Such multiple devicesmay be packaged separately or together. In another embodiment, 2 to 3different devices with antennas 104 of similarly sizes but differentshapes are supplied. The user then selects the proper device. In analternate embodiment, the deployment of the device is tailored to theparticular target tissue or cavity. In such embodiments, whole or partsof antenna 104 is designed to be deployed in a particular size and/orshape that best fits the particular target tissue or cavity.

Any of the antennas 104 disclosed herein may or may not lie in the planeof the distal region of coaxial cable 102. For example, in FIG. 1A,ablation device 100 may be pre-shaped such that antenna 104 lies in theplane of the distal region of coaxial cable 102. In an alternateembodiment, antenna 104 is oriented at an angle to the plane of thedistal region of coaxial cable 102. For example, antenna 104 may beoriented at an angle ranging from about 20 degrees to about 90 degreesto the plane of the distal region of coaxial cable 102. The orientationof antenna 104 relative to the orientation of the distal region ofcoaxial cable 102 or the shaft of ablation device 100 may be relativelyconstant or may be adjustable by the user. In one such embodiment,ablation device 100 is provided with a deflecting or steering mechanismto controllably change the orientation of antenna 104 relative to theorientation of the distal region of coaxial cable 102 or the shaft ofablation device 100.

In any of the devices disclosed herein, instead of coaxial cable 102, analternate element for transmitting microwaves may be used. Examples ofsuch alternate elements for transmitting microwaves include, but are notlimited to: waveguides, micro strip lines, strip lines, coplanarwaveguide and rectax. In such embodiments, shaping element 114 may beelectrically connected to a portion of the shielding element of thetransmission line. In a coaxial cable, the shielding element is theouter conductor. In a strip line, wherein the shielding element is thecombination of the two ground planes, shaping element(s) 114 may be inelectrical conduction with the combination of the two ground planes. Ina hollow metallic waveguide, wherein the shielding element is theelectrically conducting wall, shaping element(s) 114 may be inelectrical conduction with the electrically conducting wall.

Any of the devices disclosed herein may comprise an impedance and/ortemperature measuring modality. In one embodiment, a device disclosedherein comprises a radiometric temperature sensing modality. Thisradiometric temperature sensing modality may be used to non-invasivelymeasure of temperature at the surface or at a deeper region of tissue.This in turn can be used to obtain real-time feedback about theeffectiveness of energy delivery by the device.

One or more elements described herein may comprise one or moreadditional treatment modalities. Examples of such additional treatmentmodalities include, but are not limited to: radiofrequency electrodesincluding radiofrequency ablation electrodes, heating elements,cryotherapy elements, elements for emitting laser and other radiation,elements for introducing one or more fluids, etc. For example, outerloop 112 and/or center loop 114 may comprise multiple radiofrequencyablation electrodes. Such radiofrequency ablation electrodes enable theuse of the devices disclosed herein in conjunction with other modalitiessuch as radiofrequency ablation. One or more elements described hereinmay comprise one or more additional diagnostic modalities. Examples ofsuch diagnostic modalities include, but are not limited to: temperaturesensors, impedance sensors, electrophysiological signal sensors,visualization elements, etc. For example, outer loop 112 and/or centerloop 114 may comprise multiple temperature sensors.

In addition to endometrial ablation, the devices and methods disclosedherein may be used for liver ablations for treating liver tumors, skinablations for treating wrinkles, cardiac tissue ablations for treatingatrial fibrillation, Ventricular Tachycardia, Bradycardia and otherarrhythmias. The devices and methods disclosed herein may be used fordeeper heating to cause tissue shrinkage for treating conditions such asfecal incontinence, GERD, urinary incontinence, etc. Such deeper heatingmay be carried out within lumens or other bodily cavities.

Various additional embodiments of antenna 104 may be designed whereinthe radiating element is a straight or curved or bent or pre-shapedmonopole antenna.

Several examples or embodiments of the invention have been discussedherein, but various modifications, additions and deletions may be madeto those examples and embodiments without departing from the intendedspirit and scope of the invention. Thus, any element, component, methodstep or attribute of one method or device embodiment may be incorporatedinto or used for another method or device embodiment, unless to do sowould render the resulting method or device embodiment unsuitable forits intended use. If the various steps of a method are disclosed in aparticular order, the various steps may be carried out in any otherorder unless doing so would render the method embodiment unsuitable forits intended use. Various reasonable modifications, additions anddeletions of the described examples or embodiments are to be consideredequivalents of the described examples or embodiments.

1. (canceled)
 2. A medical antenna for applying energy to tissue from anenergy source through a transmission line, the device comprising: afirst conductor coupled to the transmission line and set in a firstplanar loop shape, where the first planar loop shape comprises a basesection that extends transversely to a longitudinal axis of thetransmission line; a second conductor electrically grounded andelectrically insulated from the first conductor, where the secondconductor comprises a second planar loop shape, the second conductorextending adjacent to the first conductor such that during applicationof energy to the first conductor, the second conductor is configured toalter output of the first conductor to produce a uniform microwave fieldabout the first planar loop shape; and where the first planar loop shapeflexes when the first conductor is advanced against the tissue allowingthe base section to conform to the tissue while allowing the firstconductor to remain in the planar loop shape.
 3. The medical antenna ofclaim 2, where the second conductor alters output of the first conductorsuch that the uniform microwave field comprises a volumetric microwavefield.
 4. The medical antenna of claim 2, wherein volumetric microwavefield that applies energy to an entire surface of the tissue cavity in asingle activation without repositioning.
 5. The medical antenna of claim2, wherein the antenna is flexible to deform to a first undeployedconfiguration when constrained and return to the planar loop shape whenunconstrained.
 6. The medical antenna of claim 3, where the secondplanar loop shape comprises a series of rounded edges.
 7. The medicalantenna of claim 2, where the planar loop shape comprises a series ofrounded edges.
 8. The medical antenna of claim 2, wherein a distalregion of the first planar loop shape is substantially wider than aproximal region of the first planar loop shape in an unconstrainedconfiguration.
 9. The medical antenna of claim 2, wherein the antennacomprises a component with shape memory characteristics.
 10. The medicalantenna of claim 2, further comprising a delivery sheath, where theantenna is slidably advanceable through the delivery sheath.
 11. Themedical antenna of claim 10, further comprising a cooling source coupledto the delivery sheath.
 12. The medical antenna of claim 10, furthercomprising a vacuum source coupled to the delivery sheath.
 13. Themedical antenna of claim 2, wherein the first conductor is covered witha dielectric material.
 14. The medical antenna of claim 13, wherein thefirst conductor is entirely covered with the dielectric material. 15.The medical antenna of claim 2, wherein the first conductor iselectrically insulated from surrounding tissue.
 16. The medical antennaof claim 2, wherein the uniform microwave field comprises a frequencylying in an ISM band selected from the group consisting of: 0.915 GHzISM band, 0.433 GHz ISM band, 2.45 GHz ISM band and 5.8 GHz ISM band 17.The medical antenna of claim 2, wherein the total length of firstconductor is one of: one quarter or three quarters of the effectivewavelength of the microwave energy delivered by the device.
 18. Themedical device of claim 2, wherein the device is connected to agenerator, wherein the generator is capable of varying the magnitude ofpower delivery with time
 19. The medical device of claim 2, where thesecond conductor is coupled to the transmission line.
 20. A method ofdelivering energy to a surface of a tissue, the method comprising:inserting a microwave ablation device adjacent to the surface of thetissue, where the microwave ablation device comprising a microwaveantenna, where the microwave antenna comprises a first conductor set ina planar loop shape when unconstrained and a shaping element where adistal region of the first conductor extends transversely to alongitudinal axis of the microwave antenna; positioning the firstconductor against the surface of the cavity such that distal region ofthe first the conductor conforms to the surface of the tissue and wherea flexibility of the first conductor permits a reminder of the firstconductor to remain in the planar loop shape; and applying energy to themicrowave antenna where the shaping element alters the energy output ofthe first conductor to produce a volumetric microwave field to deliverenergy to the tissue.
 21. The method of claim 20, further comprisingselecting a profile of the planar loop shape based upon a shape of thetissue.
 22. The method of claim 20, further comprising selecting aprofile of the shaping element based upon a shape of the tissue.
 23. Themethod of claim 20, where the tissue comprises tissue in a uterinecavity and where the profile of the planar loop shape is similar to ashape of the uterine cavity.
 24. The method of claim 23 where insertingthe microwave ablation device comprises placing the microwave ablationdevice within a uterine cavity such that a plane of the microwaveantenna is substantially parallel to a plane of the uterine cavity. 25.The method of claim 20, where applying energy comprises generating thevolumetric microwave field to provide a therapeutically effective amountof energy to the tissue without repositioning the microwave antenna. 26.The method of claim 20, wherein the antenna is configured to generatethe volumetric microwave field similar to a shape of an endometrium. 27.The method of claim 20, wherein the volumetric microwave field producesan endometrial ablation pattern being s deeper in a center of a uterinecavity and shallower at cornual regions and a lower uterine region. 28.The method of claim 27, further comprising applying suction to collapsethe uterine cavity.
 29. The method of claim 28, further comprisingfluidly sealing an opening to the uterine cavity to assist in collapsingthe cavity.
 30. The method of claim 20, where inserting the microwaveantenna further comprises advancing a delivery sheath and deploying themicrowave antenna through the delivery sheath.
 31. The method of claim30, further comprising applying a cooling fluid through the deliverysheath to cool the surface of the cavity.